Coronavirus vaccine compositions, methods, and uses thereof

ABSTRACT

The present disclosure relates in some aspects to immunogenic compositions including recombinant peptides and proteins comprising coronavirus viral antigens and immunogens, e.g., coronavirus S protein peptides. In some aspects, the immunogenic composition comprises a secreted fusion protein comprising a soluble coronavirus viral antigen joined by in-frame fusion to a C-terminal portion of a collagen which is capable of self-trimerization to form a disulfide bond-linked trimeric fusion protein. In some aspects, the immunogenic compositions provided herein are useful for generating an immune response, e.g., for treating or preventing a coronavirus infection. In some aspects, the immunogenic compositions provided herein may be used in a vaccine composition, e.g., as part of a prophylactic and/or therapeutic vaccine. Also provided herein are methods for producing the recombinant peptides and proteins, prophylactic, therapeutic, and/or diagnostic methods, and related kits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent Application No. PCT/CN2021/099285, filed Jun. 10, 2021, which claims priority to and the benefit of International Patent Application Nos. PCT/CN2020/095269, filed Jun. 10, 2020; PCT/CN2021/087066, filed Apr. 13, 2021; and PCT/CN2021/093895, filed May 14, 2021, the disclosures of which applications are incorporated herein by reference in their entireties for all purposes.

SUBMISSION OF SEQUENCE LISTING AS ASCII TEXT FILE

The content of the following submission on ASCII text file is incorporated herein by reference in its entirety: a computer readable form (CRF) of the Sequence Listing (file name: 165762000101SEQLIST.TXT, date recorded: Sep. 28, 2021, size: 575 KB).

FIELD

The present disclosure relates in some aspects to immunogenic compositions including recombinant peptides and proteins comprising coronavirus viral antigens and immunogens, e.g., coronavirus S protein peptides, for treating and/or preventing a coronavirus infection.

BACKGROUND

Coronaviruses infect a wide range of avian and mammalian species, including humans. Coronaviruses may circulate annually in humans and generally cause mild respiratory diseases, although severity can be greater in infants, elderly, and the immunocompromised. However, certain coronaviruses, including the Middle East respiratory syndrome coronavirus (MERS-CoV), the severe acute respiratory syndrome coronavirus (SARS-CoV-1), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are highly pathogenic. The high pathogenicity, airborne transmissibility, high case-fatality rate, and vaguely defined epidemiology against coronaviruses have created an urgent need for an effective vaccine and related therapeutic agents. In particular, vaccines that are able to rapidly induce effective immune responses against SARS-CoV-2 is urgently needed. Provided are methods, uses and articles of manufacture that meet such and other needs.

SUMMARY

In some embodiments, disclosed herein is a protein comprising a plurality of recombinant polypeptides, each recombinant polypeptide comprising a surface antigen of a coronavirus linked to a C-terminal propeptide of collagen, wherein the C-terminal propeptides of the recombinant polypeptides form inter-polypeptide disulfide bonds.

In some embodiments, disclosed herein are recombinant subunit vaccines that comprise an ecto-domain (e.g., without transmembrane and cytoplasmic domains) of an S protein or its fragments from a coronavirus, such as SARS-CoV-2, which is fused in-frame to a C-propeptide of a collagen that is capable of forming disulfide bond-linked homo-trimer. The resulting recombinant subunit vaccines, such as an S-Trimer™, can be expressed and purified from transfected cells, and are expected to be in native-like conformation in trimeric form. This solves the problems of mis-folding of a viral antigen often encountered when it is expressed as a recombinant peptide or protein in soluble forms without the transmembrane and/or cytoplasmic domains. Such mis-folded viral antigens do not faithfully preserve the native viral antigen conformation, and often fail to evoke neutralizing antibodies.

In some embodiments, the coronavirus is a Severe Acute Respiratory Syndrome (SARS)-coronavirus (SARS-CoV-1), a SARS-coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, a Middle East Respiratory Syndrome (MERS)-coronavirus (MERS-CoV), a MERS-like coronavirus, NL63-CoV, 229E-CoV, OC43-CoV, HKU1-CoV, WIV1-CoV, MHV, HKU9-CoV, PEDV-CoV, or SDCV.

In any of the preceding embodiments, the surface antigen can comprise a coronavirus spike (S) protein or a fragment or epitope thereof, wherein the epitope is optionally a linear epitope or a conformational epitope, and wherein the protein comprises three recombinant polypeptides.

In any of the preceding embodiments, the surface antigen can comprise a signal peptide, an S1 subunit peptide, an S2 subunit peptide, or any combination thereof.

In any of the preceding embodiments, the surface antigen can comprise a signal peptide, a receptor binding domain (RBD) peptide, a receptor binding motif (RBM) peptide, a fusion peptide (FP), a heptad repeat 1 (HR1) peptide, or a heptad repeat 2 (HR2) peptide, or any combination thereof.

In any of the preceding embodiments, the surface antigen can comprises a receptor binding domain (RBD) of the S protein.

In any of the preceding embodiments, the surface antigen can comprise an S1 subunit and an S2 subunit of the S protein.

In any of the preceding embodiments, the surface antigen can be free of a transmembrane (TM) domain peptide and/or a cytoplasm (CP) domain peptide.

In any of the preceding embodiments, the surface antigen can comprise a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, thrombin, or cathepsin L.

In any of the preceding embodiments, the surface antigen can be free of a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, thrombin, or cathepsin L, or can contain a mutated protease cleavage site that is not cleavable by the protease.

In any of the preceding embodiments, the surface antigen can be soluble or do not directly bind to a lipid bilayer, e.g., a membrane or viral envelope.

In any of the preceding embodiments, the surface antigens can be the same or different among the recombinant polypeptides of the protein.

In any of the preceding embodiments, the surface antigen can be directly fused to the C-terminal propeptide, or can be linked to the C-terminal propeptide via a linker, such as a linker comprising glycine-X-Y repeats, wherein X and Y and independently any amino acid and optionally proline or hydroxyproline.

In any of the preceding embodiments, the protein can be soluble or do not directly bind to a lipid bilayer, e.g., a membrane or viral envelope.

In any of the preceding embodiments, the protein can bind to a cell surface receptor of a subject, optionally wherein the subject is a mammal such as a primate, e.g., human.

In any of the preceding embodiments, the cell surface receptor can be angiotensin converting enzyme 2 (ACE2), dipeptidyl peptidase 4 (DPP4), dendritic cell-specific intercellular adhesion molecule-3-grabbing non integrin (DC-SIGN), or liver/lymph node-SIGN (L-SIGN).

In any of the preceding embodiments, the C-terminal propeptide can be of human collagen.

In any of the preceding embodiments, the C-terminal propeptide can comprise a C-terminal polypeptide of proα1(I), proα1(II), proα1(III), proα1(V), proα1(XI), proα2(I), proα2(V), proα2(XI), or proα3(XI), or a fragment thereof.

In any of the preceding embodiments, the C-terminal propeptides can be the same or different among the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise any of SEQ ID NOs: 67-80, or an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 99.5% sequence homology to any of SEQ ID NOs: 67-80, capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 67 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 68 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 69 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 70 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 71 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 72 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 73 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 74 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 75 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 76 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 77 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 78 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 79 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise SEQ ID NO: 80 or an amino acid sequence at least 95% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the C-terminal propeptide can comprise a sequence comprising glycine-X-Y repeats linked to the N-terminus of any of SEQ ID NOs: 67-80, wherein X and Y and independently any amino acid and optionally proline or hydroxyproline, or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

In any of the preceding embodiments, the surface antigen in each recombinant polypeptide can be in a prefusion conformation.

In any of the preceding embodiments, the surface antigen in each recombinant polypeptide can be in a postfusion conformation.

In any of the preceding embodiments, the surface antigen in each recombinant polypeptide can comprise any of SEQ ID NOs: 27-66 or an amino acid sequence at least 80% identical thereto.

In any of the preceding embodiments, the recombinant polypeptide can comprise any of SEQ ID NOs: 1-26 or an amino acid sequence at least 80% identical thereto.

Also provided herein is an immunogen comprising a protein provided herein. Provided herein is a protein nanoparticle comprising protein provided herein directly or indirectly linked to a nanoparticle. Provided herein is a virus-like particle (VLP) comprising a protein provided herein.

Also provided herein is an isolated nucleic acid encoding one, two, three or more of the recombinant polypeptides of the protein provided herein. In some embodiments, a polynucleotide encoding the S protein peptide is fused in-frame to a polynucleotide encoding the C-terminal propeptide of collagen. In some embodiments, the isolated nucleic acid provided herein is operably linked to a promoter.

In some embodiments, the isolated nucleic acid provided herein is a DNA molecule. In some embodiments, the isolated nucleic acid provided herein is an RNA molecule, optionally an mRNA molecule such as a nucleoside-modified mRNA, a non-amplifying mRNA, a self-amplifying mRNA, or a trans-amplifying mRNA.

Also provided herein is a vector comprising an isolated nucleic acid provided herein. In some embodiments, the vector is a viral vector.

In some aspects, provided herein is a virus, a pseudovirus, or a cell comprising vector provided herein, optionally wherein the virus or cell has a recombinant genome. In some aspects, provided herein is an immunogenic composition comprising the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, or cell provided herein, and a pharmaceutically acceptable carrier.

Also provided herein is a vaccine comprising an immunogenic composition provided herein and optionally an adjuvant, wherein the vaccine is optionally a subunit vaccine. In some embodiments, the vaccine is a prophylactic and/or therapeutic vaccine.

In some aspects, provided herein is a method of producing a protein, comprising: expressing the isolated nucleic acid or vector provided herein in a host cell to produce the protein as provided herein; and purifying the protein. Provided herein is a protein produced by a method provided herein.

Provided herein are methods for generating an immune response to an S protein peptide or fragment or epitope thereof of a coronavirus in a subject, comprising administering to the subject an effective amount of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine as provided herein to generate the immune response. In some embodiments, the method provided herein is for treating or preventing infection with the coronavirus. In some embodiments, generating the immune response inhibits or reduces replication of the coronavirus in the subject. In some embodiments, the immune response comprises a cell-mediated response and/or a humoral response, optionally comprising production of one or more neutralizing antibody, such as a polyclonal antibody or a monoclonal antibody. In some embodiments, the immune response is against the S protein peptide or fragment or epitope thereof of the coronavirus but not against the C-terminal propeptide. In some embodiments, the administering to the subject does not lead to antibody dependent enhancement (ADE) in the subject due to prior exposure to one or more coronavirus. In some embodiments, the administering does not lead to antibody dependent enhancement (ADE) in the subject when subsequently exposed to one or more coronavirus. In some embodiments, the method further comprises a priming step and/or a boosting step. In some embodiments, the administering step is performed via topical, transdermal, subcutaneous, intradermal, oral, intranasal (e.g., intranasal spray), intratracheal, sublingual, buccal, rectal, vaginal, inhaled, intravenous (e.g., intravenous injection), intraarterial, intramuscular (e.g., intramuscular injection), intracardiac, intraosseous, intraperitoneal, transmucosal, intravitreal, subretinal, intraarticular, peri-articular, local, or epicutaneous administration. In some embodiments, the effective amount is administered in a single dose or a series of doses separated by one or more interval. In some embodiments, the effective amount is administered without an adjuvant. In some embodiments, the effective amount is administered with an adjuvant.

Provided herein are methods comprising administering to a subject an effective amount of a protein provided herein to generate in the subject a neutralizing antibody or neutralizing antisera to the coronavirus. In some embodiments, the subject is a mammal, optionally a human or a non-human primate. In some embodiments, the method further comprises isolating the neutralizing antibody or neutralizing antisera from the subject. In some embodiments, the method further comprises administering an effective amount of the isolated neutralizing antibody or neutralizing antisera to a human subject via passive immunization to prevent or treat an infection by the coronavirus. In some embodiments, the neutralizing antibody or neutralizing antisera to the coronavirus comprises polyclonal antibodies to the coronavirus S protein peptide or fragment or epitope thereof, optionally wherein the neutralizing antibody or neutralizing antisera is free or substantially free of antibodies to the C-terminal propeptide of collagen. In some embodiments, the neutralizing antibody comprises a monoclonal antibody to the coronavirus S protein peptide or fragment or epitope thereof, optionally wherein the neutralizing antibody is free or substantially free of antibodies to the C-terminal propeptide of collagen.

In some aspects, the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine provided herein, is for use in inducing an immune response to a coronavirus in a subject, and/or in treating or preventing an infection by the coronavirus.

In some aspects, provided herein is use of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine provided herein, for inducing an immune response to a coronavirus in a subject, and/or for treating or preventing an infection by the coronavirus. In some aspects, provided herein is use of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine provided herein, for the manufacture of a medicament or a prophylactic for inducing an immune response to a coronavirus in a subject, and/or for treating or preventing an infection by the coronavirus.

Also provided herein are methods for analyzing a sample, comprising: contacting a sample with the protein provided herein, and detecting a binding between the protein and an analyte capable of specific binding to the S protein peptide or fragment or epitope thereof of the coronavirus. In some embodiments, the analyte is an antibody, a receptor, or a cell recognizing the S protein peptide or fragment or epitope thereof. In some embodiments, the binding indicates the presence of the analyte in the sample, and/or an infection by the coronavirus in a subject from which the sample is derived.

Provided herein are kits comprising the protein provided herein and a substrate, pad, or vial containing or immobilizing the protein, optionally wherein the kit is an ELISA or lateral flow assay kit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows structural features of an exemplary soluble S-Trimer™ subunit vaccine for SARS-CoV-2. (A) Schematic illustration of the structural domains of S-Trimer™ and (B) its trimeric and covalently-linked three-dimensional conformation.

FIG. 2 shows high-level expression of an exemplary S-Trimer™. The full-length S-Trimer™ and partially cleaved forms at S1/S2 furin site, namely the S2-Trimer™ and the cleaved S1 fragment, are indicated.

FIG. 3 shows the purification and characterization of an exemplary covalently linked S-Trimer™. (A) S-Trimer™ was purified from the cleared cell cultured medium via a Protein A (PA) affinity chromatography and anion exchange column (Q) followed by ultra-filtration and diafiltration (UF/DF) to obtain the drug substance (DS). (B) S-Trimer™ is a disulfide bond-linked trimer. (C) The S-Trimer™ was purified to nearly homogeneity as judged by SEC-HPLC analysis, with some cleaved S1 being separated during the size exclusion chromatography. (D) The receptor binding kinetics of S-Trimer™ to ACE2-Fc was assessed.

FIG. 4 shows an exemplary S-Trimer™ is highly glycosylated with N-linked glycans. The full-length S-Trimer™, S2-Trimer™ and cleaved S1 before and after deglycosylation are indicated.

FIG. 5 shows Electron Micrographs (EM) of an exemplary S-Trimer™ and the predicted conformation of the S-Trimer™ (right cartoon).

FIG. 6 shows the detection of S-specific antibodies and neutralizing antibodies from convalescent sera using an exemplary S-Trimer™ as an antigen.

FIG. 7A and FIG. 7B show the induction of antigen-specific antibodies and neutralizing antibodies, respectively, in rats, with an exemplary S-Trimer™ alone and without any adjuvant. FIG. 7C shows induction of antigen-specific antibodies with an exemplary S-Trimer™ vaccine in mice, without adjuvant or with Alum (aluminum hydroxide) as the adjuvant. FIG. 7D and FIG. 7E show the induction of antigen-specific antibodies and neutralizing antibodies, respectively, in rats, with an exemplary S-Trimer™ adjuvanted with a squalene-based adjuvant.

FIG. 8 shows the structure and certain sequences of exemplary coronaviruses.

FIG. 9 shows the detection of SARS-CoV-2 neutralizing antibodies and ACE2-competitive titers in human COVID-19 convalescent sera. 8 human convalescent sera (HCS) samples with moderate-to-high antibody titers collected from COVID-19 patients infected with original strain (Wuhan-Hu-1) were analyzed for (A) SARS-CoV-2 pseudovirus neutralization titers and (B) ACE2-competitive ELISA titers based on the original (Wuhan-Hu-1), UK (B.1.1.7), South African (B.1.351) and Brazil (P.1) strains. Data are presented comparing variant strains titers to original strain titers. Dots represent data for individual HCS samples, and bars represent geometric mean titers (GMT) of half maximal effective concentration (EC₅₀) values. Error bars represent 95% confidence intervals (95% CI).

FIG. 10 shows prototype and modified B.1.351 S-Trimer™ antigens and mouse immunogenicity study design. (A) Schematic representations of Prototype S-Trimer™ and the modified B.1.351 S-Trimer™ containing 3 RBD mutations and the D614G mutations in the B.1.351 variant. (B) Determination of the binding affinity (K_(D)) between S-Trimer™ (Prototype and B.1.351) and human ACE2-Fc by ForteBio BioLayer interferometry. (C) BALB/c mice (n=16-32/group) were immunized in Stage 1 of the study with either two doses of Prototype S-Trimer™ (3 μg), heterologous prime-boost (dose 1 Prototype S-Trimer™; dose 2 B.1.351 S-Trimer™; 3 μg of each antigen), two doses B.1.351 S-Trimer™ (3 μg), or two doses of bivalent vaccine (3 μg Prototype S-Trimer™ mixed with 3 μg B.1.351 S-Trimer™). All animals in Stage 1 received an adjuvanted priming dose (Dose 1) comprising Alum (aluminum hydroxide). For the boost (Dose 2), half of the animals in each group received an adjuvanted boost comprising Alum (aluminum hydroxide), and the other half received non-adjuvanted boost (antigen-only). In Stage 2 of the study, animals in group 1 were randomized to receive a booster dose (Dose 3) with either 3 μg Prototype S-Trimer™ or 3 μg B.1.351 S-Trimer™ (half adjuvanted and half non-adjuvanted). Animals in groups 2-3 were randomized to receive a booster (Dose 3) with either 3 μg of non-adjuvanted Prototype or B.1.351 S-Trimer™. (D) BALB/c mice were immunized in Stage 1 with priming (Dose 1) on day 0 and boost (Dose 2) on day 21, with primary analysis for humoral immunogenicity was conducted on day 35 blood samples. In Stage 2, a booster dose (Dose 3) was given on day 35 and primary analysis for humoral and cellular immune responses was conducted on day 49 blood samples.

FIG. 11 shows humoral immune response of 2 doses of prototype and/or B.1.351 Spike-Trimer™ antigens in mice. Humoral immune responses in Stage 1 of the study were evaluated on Day 35 (2 weeks after dose 2) based on (A) SARS-CoV-2 pseudovirus neutralization assays against original strain, UK (B.1.1.7), South African (B.1.351) and Brazil (P.1) strains and (B) ACE2-competitive ELISA detecting competition of vaccine-induced antibodies for binding to ACE2 with S-Trimer™ based on Original (Wuhan-Hu-1), UK (B.1.1.7), South African (B.1.351) and Brazil (P.1) strains. Dots represent individual animals; bars represent geometric mean titers (GMT) of EC₅₀ values, and error bars represent 95% confidence intervals (95% CI). Fold differences (A) in GMTs for groups 2-4 compared to group 1 (Prototype S-Trimer™) are shown, and statistically-significant differences are shown in black text. P values<0.05 were considered significant.

FIG. 12 shows effect of adjuvants on humoral immune response for boost (Dose 2) and booster (Dose 3). Humoral immune responses in the study were evaluated based on SARS-CoV-2 pseudovirus neutralization assays against original strain, UK (B.1.1.7), South African (B.1.351) and Brazil (P.1) strains. Results for pseudovirus neutralization titers based on factorial analyses and are shown here for (A) Stage 1 where all animals received an adjuvanted priming dose (Dose 1) comprising Alum (aluminum hydroxide), whereas half of the animals received an adjuvanted boost (Dose 2) comprising Alum (aluminum hydroxide), and the remaining half of the animals received non-adjuvanted boost (antigen-only), and (B) Stage 2 where half of the animals in Group 1 received an adjuvanted booster Dose 3 comprising Alum (aluminum hydroxide) and the remaining half of the animals received non-adjuvanted booster (antigen-only). Dots represent individual animals; bars represent geometric mean titers (GMT) of EC₅₀ values, and error bars represent 95% confidence intervals (95% CI). P values<0.05 were considered significant.

FIG. 13 shows humoral immune response of 3 doses of prototype and/or B.1.351 Spike-Trimer™ antigens in mice. Humoral immune responses in Stage 2 of the study were evaluated in animals receiving a non-adjuvanted booster (Dose 3) on Day 49 (2 weeks after Dose 3) based on SARS-CoV-2 pseudovirus neutralization assays against (A) Original (Wuhan-Hu-1) strain, (B) UK (B.1.1.7) variant, (C) South African (B.1.351) variant and (D) Brazil (P.1) variant pseudoviruses. Neutralization titers on Day 35 (2 weeks after Dose 2) are also shown. Fold differences in titers (Day 49 versus Day 35) in each booster group are shown. Dots represent individual animals; bars represent geometric mean titers (GMT) of half maximal effective concentration (EC₅₀) values, and error bars represent 95% confidence intervals (95% CI).

FIG. 14 shows cell-mediated immune responses of 3 doses of prototype or B.1.351 Spike-Trimer™ antigens in mice. Cell-mediated immune responses in Stage 2 of the study were evaluated on Day 49 (2 weeks after dose 3) based on ELISpot detecting Th1 cytokines (IFNγ and IL-2) or Th2 cytokine (IL-5) in harvested splenocytes stimulated with (A) S1 peptide pool from original (Wuhan-Hu-1) strain, (B) S1 peptide pool from SARS-CoV, (C) RBD peptide pool from B.1.351 variant, or (D) RBD peptide pool from P.1 variant. Dots represent individual animals; bars represent group mean values, and error bars represent 95% confidence intervals (95% CI).

FIG. 15 shows cross-neutralization based on pseudovirus neutralization titers after 2 doses of prototype and/or B.1.351 S-Trimer™ antigens in mice. Humoral immune responses in Stage 1 of the study were evaluated on Day 35 (2 weeks after dose 2) based on SARS-CoV-2 pseudovirus neutralization assays against original strain, UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1) strains. Results are shown for (A) Group 1 (two doses of Prototype S-Trimer™), (B) Group 2 (heterologous prime-boost), (C) Group 3 (two doses B.1.351 S-Trimer™), or (D) two doses of bivalent vaccine. Results from individual animals are represented by dots in each figure, with lines connecting the Original and variant neutralization titers. Geometric mean titers (GMT) of EC₅₀ values are shown, and error bars represent 95% confidence intervals (95% CI). P values<0.05 were considered significant (n.s., not significant).

FIG. 16 shows cross-neutralization based on ACE2-competitive titers after 2 doses of prototype and/or B.1.351 S-Trimer™ antigens in mice. Humoral immune responses in Stage 1 of the study were evaluated on Day 35 (2 weeks after dose 2) based on ACE2-competitive ELISA assays against original strain, UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1) strains. Results are shown for (A) Group 1 (two doses of Prototype S-Trimer™), (B) Group 2 (heterologous prime-boost), (C) Group 3 (two doses B.1.351 S-Trimer™), or (D) two doses of bivalent vaccine. Results from individual animals are represented by dots in each figure, with lines connecting the Original and variant neutralization titers. Geometric mean titers (GMT) of EC₅₀ values are shown, and error bars represent 95% confidence intervals (95% CI). P values<0.05 were considered significant (n.s., not significant).

FIG. 17 shows humoral immune response after 2 doses of prototype and/or B.1.351 S-Trimer™ antigens in mice. Humoral immune responses in Stage 1 of the study were evaluated on Day 35 (2 weeks after dose 2) based on SARS-CoV-2 pseudovirus neutralization assays against (A) original strain, (B) UK variant (B.1.1.7), (C) South African variant (B.1.351) and (D) Brazil variant (P.1) strains. All animals in Stage 1 received an adjuvanted priming dose (Dose 1) comprising Alum (aluminum hydroxide), whereas half of the animals in each group received an adjuvanted boost (Dose 2) comprising Alum (aluminum hydroxide), and the other half received non-adjuvanted boost (antigen-only). Results here are shown for subgroups of animals receiving either adjuvanted or non-adjuvanted boost (dose 2). Dots represent individual animals; bars represent geometric mean titers (GMT) of EC₅₀ values, and error bars represent 95% confidence intervals (95% CI). P values<0.05 were considered significant.

FIG. 18 shows humoral immune response after 3 doses of prototype and/or B.1.351 S-Trimer™ antigens in mice. Humoral immune responses in Stage 2 of the study were evaluated on Day 49 (2 weeks after dose 3) based on SARS-CoV-2 pseudovirus neutralization assays against (A) Original (Wuhan-Hu-1) strain, (B) UK (B.1.1.7) variant, (C) South African (B.1.351) variant and (D) Brazil (P.1) variant pseudoviruses. Results here are shown for all subgroups (representing all vaccination combinations) in the study (n=4/subgroup). Dots represent individual animals; bars represent geometric mean titers (GMT) of EC₅₀ values, and error bars represent 95% confidence intervals (95% CI).

DETAILED DESCRIPTION

Provided herein are immunogenic compositions, methods, and uses of fusion peptides and proteins comprising coronavirus viral antigens or immunogens for the treatment, e.g., prophylactic, therapeutic, of coronavirus infections. In some embodiments, compositions and methods of use of recombinant soluble surface antigens from RNA viruses in covalently linked trimeric forms are disclosed. In some embodiments, the resulting fusion proteins are secreted as disulfide bond-linked homo-trimers, which are more stable in structure, while preserving the conformations of native-like trimeric viral antigens, thereby can be used as more effective vaccines against these dangerous pathogens.

In some embodiments, disclosed herein are methods for using viral antigen trimers as a vaccine or as part of a multivalent vaccine to prevent viral infections, without or with adjuvant, or with more than one adjuvant, optionally via either intra-muscular injections or intra-nasal administrations.

In some embodiments, disclosed herein are methods for using viral antigen trimers as an antigen for diagnosis of viral infections through detection of antibodies, e.g., IgM or IgG, that recognize the viral antigen, such as neutralizing antibodies.

In some embodiments, disclosed herein are methods for using viral antigen trimers as an antigen to generate polyclonal or monoclonal antibodies which can be used for passive immunization, e.g., neutralizing mAb for treating a coronavirus infection.

In some embodiments, disclosed herein is a viral antigen trimer as a vaccine or as part of a multivalent vaccine, wherein the vaccine comprises a plurality of trimeric subunit vaccines comprising viral antigens of the same protein of a virus or comprising viral antigens of two or more different proteins of one or more viruses or one or more strains of the same virus.

In some embodiments, disclosed herein is a monovalent vaccine comprising a viral antigen trimer disclosed herein. In some embodiments, disclosed herein is a bi-valent vaccine comprising a viral antigen trimer disclosed herein. In some embodiments, disclosed herein is a tri-valent vaccine comprising a viral antigen trimer disclosed herein. In some embodiments, disclosed herein is a quadrivalent vaccine comprising a viral antigen trimer disclosed herein.

In some embodiments, disclosed herein is a monovalent vaccine comprising an S-Trimer™ disclosed herein. In some embodiments, disclosed herein is a bi-valent vaccine comprising an S-Trimer™ disclosed herein. In some embodiments, disclosed herein is a bi-valent vaccine comprising at least one S-Trimer™ comprising a first S protein antigen and at least one S-Trimer™ comprising a second S protein antigen. In some embodiments, the first and second S protein antigens are from the same S protein of one or more virus species or strains/subtypes, or from two or more different S proteins of one or more virus species or one or more strains/subtypes of the same virus species. In some embodiments, disclosed herein is a tri-valent vaccine comprising an S-Trimer™ disclosed herein. In some embodiments, disclosed herein is a tri-valent vaccine comprising at least one S-Trimer™ comprising a first S protein antigen, at least one S-Trimer™ comprising a second S protein antigen, and at least one S-Trimer™ comprising a third S protein antigen. In some embodiments, the first, second and third S protein antigens are from the same S protein of one or more virus species or strains/subtypes, or from two, three, or more different S proteins of one or more virus species or one or more strains/subtypes of the same virus species. In some embodiments, disclosed herein is a quadrivalent vaccine comprising an S-Trimer™ disclosed herein. In some embodiments, disclosed herein is quadrivalent vaccine comprising at least one S-Trimer™ comprising a first S protein antigen, at least one S-Trimer™ comprising a second S protein antigen, at least one S-Trimer™ comprising a third S protein antigen, and at least one S-Trimer™ comprising a fourth S protein antigen. In some embodiments, the first, second, third, and fourth S protein antigens are from the same S protein of one or more virus species or strains/subtypes, or from two, three, four, or more different S proteins of one or more virus species or one or more strains/subtypes of the same virus species.

The proteins, including recombinant polypeptides and fusion proteins, comprising coronavirus viral antigens and immunogens provided herein are useful for effectively and safely treating (e.g., therapeutically, prophylactically) coronavirus infection. For example, the proteins comprising coronavirus viral antigens and immunogens provided herein treat coronavirus infection without meditated vaccine-induced disease enhancement (VED) and/or antibody dependent enhancement (ADE). In addition, the proteins comprising coronavirus viral antigens and immunogens provided herein are easily produced, and demonstrate stability under high stress conditions such as, e.g., high temperature, extreme pH, and high and low osmolality. Thus, the proteins and immunogenic compositions provided herein circumvent and satisfy the issues of production, stability, safety, and efficacy that have hindered coronavirus vaccine development.

In some aspects, the coronavirus viral antigens and immunogens provided herein include the coronavirus Spike (S) protein or peptide, particularly SARS-CoV or SARS-CoV-2 S proteins. The spikes of SARS-CoV and SARS-CoV-2 are composed of trimers of S protein, which belongs to a group of class I viral fusion glycoproteins that also includes HIV glycoprotein 160 (Env), influenza haemagglutinin (HA), paramyxovirus F and Ebola virus glycoprotein. The SARS-CoV and SARS-CoV-2 S proteins each encodes a surface glycoprotein precursor, and the amino terminus and most of the protein is predicted to be on the outside of the cell surface or the virus particles. The S protein comprises a signal peptide located at the N terminus, an extracellular domain, a transmembrane domain and an intracellular domain. Similarly to other coronaviruses, the S protein of SARS-CoV and SARS-CoV-2 can be cleaved into the S1 and S2 subunits by proteases. In particular, SARS-CoV-2 contains a furin-like cleavage site that is lacking in the other SARS-like CoVs.

In some embodiments, provided herein are recombinant S ectodomain trimers. In some embodiments, the recombinant S ectodomain trimer comprises recombinant S ectodomain protomers from an alphacoronavirus, such as NL63-CoV or 229E-CoV. In some embodiments, the recombinant S ectodomain trimers comprise S ectodomain protomers from a betacoronavirus, such as OC43-CoV, SARS-CoV, SARS-CoV-2, MERS-CoV, HKU1-CoV, WIV1-CoV, mouse hepatitis virus (MHV), or HKU9-CoV.

Similar to other enveloped RNA viruses such as HIV, RSV and Influenza, coronaviruses including SARS-CoV-2, all each has a trimeric surface antigen on its viral envelopes to gain entry into different host cells via specific cell surface receptors during infections. Like SARS-CoV-1, SARS-CoV-2 uses its trimeric viral surface antigen S protein to enter host cells of respiratory systems in mammals upon binding to its specific cell surface receptor ACE2. The prerequisite for generating an effective recombinant subunit vaccine is to be able to create a viral S antigen that is native-like, and in particular, to maintain its trimeric conformation in order to evoke sufficient amount of antibodies that could bind to the receptor binding domain (RBD) of the viral S protein, thereby preventing the virus from binding to ACE2 receptor, thus abolishing viral infections.

In some embodiments, the protein comprising a coronavirus viral antigen or immunogen, e.g., SARS-CoV or SARS-CoV-2 S protein peptide, is capable of generating an immune response, e.g., an immune response to the SARS-CoV or SARS-CoV-2 S protein peptide. In some embodiments, the immune response inhibits or reduces replication of a coronavirus in a subject, e.g., a patient. In some embodiments, the immune response includes production of one or more neutralizing antibodies, such as polyclonal and/or monoclonal antibodies. In some embodiments, the neutralizing antibodies inhibit or reduce replication of a coronavirus in a subject, e.g., a patient. In some embodiments, administration of the protein, for example as an immunogenic composition, to the subject does not lead to antibody dependent enhancement (ADE) in the subject due to prior exposure to a coronavirus. In some aspects, the protein comprising a coronavirus viral antigen and immunogen is used as a vaccine.

In some embodiments, the coronavirus viral antigen and immunogen, e.g., SARS-CoV or SARS-CoV-2 S protein peptide, is linked to a protein or peptide to form a fusion protein or recombinant polypeptide. In some embodiments, the protein or peptide to which the coronavirus viral antigen or immunogen is linked is capable of associating, e.g., covalently or non-covalently linking, with proteins or peptides, such as proteins or peptides of fusion proteins or recombinant polypeptides. Thus, in some cases, the protein or peptide to which the coronavirus viral antigen or immunogen is linked is a multimerization domain.

In some embodiments, the coronavirus viral antigen and immunogen, e.g., coronavirus S protein peptide, is linked to a propeptide of collagen, e.g., at the C-terminal of propeptide of collagen, to form a fusion peptide or recombinant polypeptide. Thus, in some embodiments, the protein provided herein comprises recombinant polypeptides containing coronavirus viral antigens and immunogens, e.g., coronavirus S protein peptides or a fragment or epitope thereof, linked to a C-terminal propeptide of collagen. In some embodiments, the propeptide of collagen is derived from the human C-propeptide of al collagen and is capable self-trimerization upon expression.

In some embodiments, linking the coronavirus viral antigen and immunogen, e.g., coronavirus S protein peptide, to a propeptide of collagen, e.g., at the C-terminal of propeptide of collagen, aids in the ability of the protein to generate an immune response. For example, the creation of the recombinant protein may preserve the tertiary and quaternary structures of the coronavirus S protein peptide, which may be important for the stability of the native conformation of the coronavirus S protein peptide, and in turn the availability of antigenic sites on the surface of the protein capable of eliciting an immune response, e.g., neutralizing antibodies. Additionally, linking of the coronavirus S protein peptide to a protein or peptide capable of self-trimerization allows the aggregation of the recombinant proteins, thus mimicking the native homotrimeric structure of the coronavirus S protein peptides on the viral envelope.

In some embodiments, linking the coronavirus S protein peptide to a C-terminal propeptide of collagen results in self-trimerized recombinant polypeptides. In some embodiments, the protein provided herein comprises a plurality of self-trimerized coronavirus S protein peptide and propeptide of collagen recombinant polypeptides. In some embodiments, the trimeric nature of the recombinant proteins aids in the stability of the protein. In some embodiments, the trimeric nature of the recombinant proteins aids in the ability of the protein to generate an immune response. In some embodiments, the trimeric nature of the recombinant proteins and/or a macrostructure of a plurality of self-trimerized recombinant proteins aids in the ability of the protein to generate an immune response.

Also provided herein are immunogenic compositions comprising the proteins provided herein, methods of producing proteins provided herein, methods of treating subjects with proteins and compositions provided herein, and kits.

All publications, including patent documents, scientific articles and databases, referred to in this application are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication were individually incorporated by reference. If a definition set forth herein is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are herein incorporated by reference, the definition set forth herein prevails over the definition that is incorporated herein by reference. The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

I. Viral Antigens and Immunogens

The proteins provided herein comprise coronavirus viral antigens and immunogens. The coronavirus viral antigens and immunogens contemplated herein are capable of promoting or stimulating a cell-mediated response and/or a humoral response. In some embodiments, the response, e.g., cell-mediated or humoral response, comprises the production of antibodies, e.g., neutralizing antibodies. In some embodiments, the coronavirus viral antigen or immunogen is an coronavirus spike (S) protein peptide.

Coronavirus is a family of positive-sense, single-stranded RNA viruses that are known to cause severe respiratory illness. They have the largest genomes (26-32 kb) among known RNA viruses, and are phylogenetically divided into four genera (α, β, γ, δ), with betacoronaviruses further subdivided into four lineages (A, B, C, D). Viruses currently known to infect human from the coronavirus family are from the alphacoronavirus and betacoronavirus genera. Additionally, it is believed that the gammacoronavirus and deltacoronavirus genera may infect humans in the future. Non-limiting examples of betacoronaviruses include Middle East respiratory syndrome coronavirus (MERS-CoV), Severe Acute Respiratory Syndrome coronavirus (SARS-CoV), Human coronavirus HKU1 (HKU1-CoV), Human coronavirus OC43 (OC43-CoV), Murine Hepatitis Virus (MHV-CoV), Bat SARS-like coronavirus WIV1 (WIV1-CoV), and Human coronavirus HKU9 (HKU9-CoV). Non-limiting examples of alphacoronaviruses include human coronavirus 229E (229E-CoV), human coronavirus NL63 (NL63-CoV), porcine epidemic diarrhea virus (PEDV), and Transmissible gastroenteritis coronavirus (TGEV). A non-limiting example of a deltacoronaviruses is the Swine Delta Coronavirus (SDCV).

A list of Severe acute respiratory syndrome-related coronavirus is disclosed herein:

Bat coronavirus Cp/Yunnan2011

Bat coronavirus RaTG13

Bat coronavirus Rp/Shaanxi2011

Bat SARS coronavirus HKU3

-   -   Bat SARS coronavirus HKU3-1     -   Bat SARS coronavirus HKU3-10     -   Bat SARS coronavirus HKU3-11     -   Bat SARS coronavirus HKU3-12     -   Bat SARS coronavirus HKU3-13     -   Bat SARS coronavirus HKU3-2     -   Bat SARS coronavirus HKU3-3     -   Bat SARS coronavirus HKU3-4     -   Bat SARS coronavirus HKU3-5     -   Bat SARS coronavirus HKU3-6     -   Bat SARS coronavirus HKU3-7     -   Bat SARS coronavirus HKU3-8     -   Bat SARS coronavirus HKU3-9

Bat SARS coronavirus Rp1

Bat SARS coronavirus Rp2

-   -   Bat SARS CoV Rf1/2004

Bat CoV 273/2005

-   -   Bat SARS CoV Rm1/2004

Bat CoV 279/2005

Bat SARS CoV Rp3/2004

Bat SARS-like coronavirus

Bat SARS-like coronavirus Rs3367

Bat SARS-like coronavirus RsSHC014

Bat SARS-like coronavirus WIV1

Bat SARS-like coronavirus YNLF 31C

Bat SARS-like coronavirus YNLF 34C

BtRf-BetaCoV/HeB2013

BtRf-BetaCoV/JL2012

BtRf-BetaCoV/SX2013

BtRs-BetaCoV/GX2013

BtRs-BetaCoV/HuB2013

BtRs-BetaCoV/YN2013

Civet SARS CoV 007/2004

Civet SARS CoV SZ16/2003

Civet SARS CoV SZ3/2003

recombinant SARSr-CoV

-   -   SARS coronavirus ExoN1     -   SARS coronavirus MA15     -   SARS coronavirus MA15 EkoN1     -   SARS coronavirus wtic-MB

Rhinolophus affinis coronavirus

SARS bat coronavirus

SARS coronavirus A001

SARS coronavirus A013

SARS coronavirus A021

SARS coronavirus A022

SARS coronavirus A030

SARS coronavirus A031

SARS coronavirus AS

SARS coronavirus B012

SARS coronavirus B024

SARS coronavirus B029

SARS coronavirus B033

SARS coronavirus B039

SARS coronavirus B040

SARS coronavirus BJ01

SARS coronavirus BJ02

SARS coronavirus BJ03

SARS coronavirus BJ04

SARS coronavirus BJ162

SARS coronavirus BJ182-12

SARS coronavirus BJ182-4

SARS coronavirus BJ182-8

SARS coronavirus BJ182a

SARS coronavirus BJ182b

SARS coronavirus BJ202

SARS coronavirus BJ2232

SARS coronavirus BJ302

SARS coronavirus C013

SARS coronavirus C014

SARS coronavirus C017

SARS coronavirus C018

SARS coronavirus C019

SARS coronavirus C025

SARS coronavirus C028

SARS coronavirus C029

SARS Coronavirus CDC #200301157

SARS coronavirus civet010

SARS coronavirus civet014

SARS coronavirus civet019

SARS coronavirus civet020

SARS coronavirus CS21

SARS coronavirus CS24

SARS coronavirus CUHK-AG01

SARS coronavirus CUHK-AG02

SARS coronavirus CUHK-AG03

SARS coronavirus CUHK-L2

SARS coronavirus CUHK-Su10

SARS coronavirus CUHK-W1

SARS coronavirus cw037

SARS coronavirus cw049

SARS coronavirus ES191

SARS coronavirus ES260

SARS coronavirus FRA

SARS coronavirus Frankfurt 1

-   -   SARS coronavirus Frankfurt1-v01

SARS coronavirus GD01

SARS coronavirus GD03T0013

SARS coronavirus GD322

SARS coronavirus GD69

SARS coronavirus GDH-BJH01

SARS coronavirus GZ-A

SARS coronavirus GZ-B

SARS coronavirus GZ-C

SARS coronavirus GZ-D

SARS coronavirus GZ02

SARS coronavirus GZ0401

SARS coronavirus GZ0402

SARS coronavirus GZ0403

SARS coronavirus GZ43

SARS coronavirus GZ50

SARS coronavirus GZ60

SARS coronavirus HB

SARS coronavirus HC/SZ/61/03

SARS coronavirus HGZ8L1-A

SARS coronavirus HGZ8L1-B

SARS coronavirus HGZ8L2

SARS coronavirus HHS-2004

SARS coronavirus HKU-36871

SARS coronavirus HKU-39849

SARS coronavirus HKU-65806

SARS coronavirus HKU-66078

SARS coronavirus Hon Kong/03/2003

SARS coronavirus HPZ-2003

SARS coronavirus HSR 1

SARS coronavirus HSZ-A

SARS coronavirus HSZ-Bb

SARS coronavirus HSZ-Bc

SARS coronavirus HSZ-Cb

SARS coronavirus HSZ-Cc

SARS coronavirus HSZ2-A

SARS coronavirus HZS2-Bb

SARS coronavirus HZS2-C

SARS coronavirus HZS2-D

SARS coronavirus HZS2-E

SARS coronavirus HZS2-Fb

SARS coronavirus HZS2-Fc

SARS coronavirus JMD

SARS coronavirus LC1

SARS coronavirus LC2

SARS coronavirus LC3

SARS coronavirus LC4

SARS coronavirus LC5

SARS coronavirus LLJ-2004

SARS coronavirus NS-1

SARS coronavirus P2

SARS coronavirus PC4-115

SARS coronavirus PC4-127

SARS coronavirus PC4-13

SARS coronavirus PC4-136

SARS coronavirus PC4-137

SARS coronavirus PC4-145

SARS coronavirus PC4-199

SARS coronavirus PC4-205

SARS coronavirus PC4-227

SARS coronavirus PC4-241

SARS coronavirus PUMC01

SARS coronavirus PUMC02

SARS coronavirus PUMC03

SARS coronavirus Rs 672/2006

SARS coronavirus sf098

SARS coronavirus sf099

SARS coronavirus ShanghaiQXC1

SARS coronavirus ShanghaiQXC2

SARS coronavirus Shanghai LY

SARS coronavirus Sin0409

SARS coronavirus Sin2500

SARS coronavirus Sin2677

SARS coronavirus Sin2679

SARS coronavirus Sin2748

SARS coronavirus Sin2774

SARS coronavirus Sin3408

SARS coronavirus Sin3408L

SARS coronavirus Sin3725V

SARS coronavirus Sin3765V

SARS coronavirus Sin842

SARS coronavirus Sin845

SARS coronavirus Sin846

SARS coronavirus Sin847

SARS coronavirus Sin848

SARS coronavirus Sin849

SARS coronavirus Sin850

SARS coronavirus Sin852

SARS coronavirus Sin WNV

SARS coronavirus Sino1-11

SARS coronavirus Sino3-11

SARS coronavirus SinP1

SARS coronavirus SinP2

SARS coronavirus SinP3

SARS coronavirus SinP4

SARS coronavirus SinP5

SARS coronavirus SoD

SARS coronavirus SZ1

SARS coronavirus SZ13

SARS coronavirus Taiwan

SARS coronavirus Taiwan JC-2003

SARS coronavirus Taiwan TC1

SARS coronavirus Taiwan TC2

SARS coronavirus Taiwan TC3

SARS coronavirus TJ01

SARS coronavirus TJF

SARS coronavirus Tor2

SARS coronavirus TW

-   -   SARS coronavirus TW-GD1     -   SARS coronavirus TW-GD2     -   SARS coronavirus TW-GD3     -   SARS coronavirus TW-GD4     -   SARS coronavirus TW-GD5     -   SARS coronavirus TW-HP1     -   SARS coronavirus TW-HP2     -   SARS coronavirus TW-HP3     -   SARS coronavirus TW-HP4     -   SARS coronavirus TW-JC2     -   SARS coronavirus TW-KC1     -   SARS coronavirus TW-KC3     -   SARS coronavirus TW-PH1     -   SARS coronavirus TW-PH2     -   SARS coronavirus TW-YM1     -   SARS coronavirus TW-YM2     -   SARS coronavirus TW-YM3     -   SARS coronavirus TW-YM4

SARS coronavirus TW1

SARS coronavirus TW10

SARS coronavirus TW11

SARS coronavirus TW2

SARS coronavirus TW3

SARS coronavirus TW4

SARS coronavirus TW5

SARS coronavirus TW6

SARS coronavirus TW7

SARS coronavirus TW8

SARS coronavirus TW9

SARS coronavirus TWC

SARS coronavirus TWC2

SARS coronavirus TWC3

SARS coronavirus TWH

SARS coronavirus TWJ

SARS coronavirus TWK

SARS coronavirus TWS

SARS coronavirus TWY

SARS coronavirus Urbani

SARS coronavirus Vietnam

SARS coronavirus WF188

SARS coronavirus WH20

SARS coronavirus WHU

SARS coronavirus xw002

SARS coronavirus ZJ01

SARS coronavirus ZJ02

SARS coronavirus ZJ0301

SARS coronavirus ZMY 1

SARS coronavirus ZS-A

SARS coronavirus ZS-B

SARS coronavirus ZS-C

SARS-related bat coronavirus RsSHC014

SARS-related betacoronavirus Rp3/2004

Severe acute respiratory syndrome coronavirus 2

Exemplary SARS CoV-2 strains are shown in the table below.

Notable Name/Designation Distribution Mutation(s) Impact Sequence D614G Worldwide D614G Increased PODTC2 infectivity, Dominant circulating since June 2020 B.1.1.7 501Y.V1 UK/ D614G, Increased B.1.1.7 Worldwide N501Y, infectivity Lineages (nearly P681H dominant in US) B.1.351 501.V2, or South N501Y, Increased B.1.351 N501Y.V2 Africa E484K*, infectivity, Lineages K417N *escape mutation* B.1.1.248 P1 Brazil N501Y, Increased P1 E484K*, infectivity, Lineages K417T *escape mutation*

The coronavirus viral genome is capped, polyadenylated, and covered with nucleocapsid proteins. The coronavirus virion includes a viral envelope containing type I fusion glycoproteins referred to as the spike (S) protein. Most coronaviruses have a common genome organization with the replicase gene included in the 5′-portion of the genome, and structural genes included in the 3′-portion of the genome.

Coronavirus Spike (S) protein is class I fusion glycoprotein initially synthesized as a precursor protein. Individual precursor S polypeptides form a homotrimer and undergo glycosylation within the Golgi apparatus as well as processing to remove the signal peptide, and cleavage by a cellular protease to generate separate S1 and S2 polypeptide chains, which remain associated as S1/S2 protomers within the homotrimer and is therefore a trimer of heterodimers. The S1 subunit is distal to the virus membrane and contains the receptor-binding domain (RBD) that mediates virus attachment to its host receptor. The S2 subunit contains fusion protein machinery, such as the fusion peptide, two heptad-repeat sequences (HR1 and HR2) and a central helix typical of fusion glycoproteins, a transmembrane domain, and the cytosolic tail domain.

In some cases, the coronavirus viral antigen or immunogen is a coronavirus S protein peptide in a prefusion conformation, which is a structural conformation adopted by the ectodomain of the coronavirus S protein following processing into a mature coronavirus S protein in the secretory system, and prior to triggering of the fusogenic event that leads to transition of coronavirus S to the postfusion conformation. The three-dimensional structure of an exemplary coronavirus S protein (HKU1-CoV) in a prefusion conformation is provided in Kirchdoerfer et al., “Pre-fusion structure of a human coronavirus spike protein,” Nature, 531: 118-121, 2016.

In some cases, the coronavirus viral antigen or immunogen comprises one or more amino acid substitutions, deletions, or insertions compared to a native coronavirus S sequence that provide for increased retention of the prefusion conformation compared to coronavirus S ectodomain trimers formed from a corresponding native coronavirus S sequence. The “stabilization” of the prefusion conformation by the one or more amino acid substitutions, deletions, or insertions can be, for example, energetic stabilization (for example, reducing the energy of the prefusion conformation relative to the post-fusion open conformation) and/or kinetic stabilization (for example, reducing the rate of transition from the prefusion conformation to the postfusion conformation). Additionally, stabilization of the coronavirus S ectodomain trimer in the prefusion conformation can include an increase in resistance to denaturation compared to a corresponding native coronavirus S sequence. Methods of determining if a coronavirus S ectodomain trimer is in the prefusion conformation are provided herein, and include (but are not limited to) negative-stain electron microscopy and antibody binding assays using a prefusion-conformation-specific antibody.

In some cases, the coronavirus viral antigen or immunogen is a fragment of an S protein peptide. In some embodiments, the antigen or immunogen is an epitope of an S protein peptide. Epitopes include antigenic determinant chemical groups or peptide sequences on a molecule that are antigenic, such that they elicit a specific immune response, for example, an epitope is the region of an antigen to which B and/or T cells respond. An antibody can bind to a particular antigenic epitope, such as an epitope on coronavirus S ectodomain. Epitopes can be formed both from contiguous amino acids or noncontiguous amino acids juxtaposed by tertiary folding of a protein. In some embodiments, the coronavirus epitope is a linear epitope. In some embodiments, the coronavirus epitope is a conformational epitope. In some embodiments, the coronavirus epitope is a neutralizing epitope site. In some embodiments, all neutralizing epitopes of the coronavirus S protein peptide or fragment thereof are present as the antigen or immunogen.

In some cases, for example when the viral antigen or immunogen is a fragment of an S protein peptide, only a single subunit of the S protein peptide is present, and that single subunit of the S protein peptide is trimerized. In some embodiments, the viral antigen or immunogen comprises a signal peptide, an S1 subunit peptide, an S2 subunit peptide, or any combination thereof. In some embodiments, the viral antigen or immunogen comprises a signal peptide, a receptor binding domain (RBD) peptide, a receptor binding motif (RBM) peptide, a fusion peptide (FP), a heptad repeat 1 (HR1) peptide, or a heptad repeat 2 (HR2) peptide, or any combination thereof. In some embodiments, the viral antigen or immunogen comprises a receptor binding domain (RBD) of the S protein. In some embodiments, the viral antigen or immunogen comprises an S1 subunit and an S2 subunit of the S protein. In some embodiments, the viral antigen or immunogen comprises an S1 subunit of the S protein but not an S2 subunit. In some embodiments, the viral antigen or immunogen comprises an S2 subunit of the S protein but not an S1 subunit. In some embodiments, the viral antigen or immunogen is free of a transmembrane (TM) domain peptide and/or a cytoplasm (CP) domain peptide.

In some embodiments, the viral antigen or immunogen comprises a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, or cathepsin L.

In some embodiments, the viral antigen or immunogen is free of a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, or cathepsin L, or contains a mutated protease cleavage site that is not cleavable by the protease.

In some embodiments, the viral antigen or immunogen is a SARS-CoV-2 antigen comprising at least one SARS-CoV-2 protein or fragment thereof. In some embodiments, the SARS-CoV-2 antigen is recognized by SARS-CoV-2 reactive antibodies and/or T cells. In some embodiments, the SARS-CoV-2 antigen is an inactivated whole virus. In some embodiments, the SARS-CoV-2 antigen comprises is a subunit of the virus. In some embodiments, the SARS-CoV-2 antigen comprises a structural protein of SARS-CoV-2 or a fragment thereof. In some embodiments, the structural protein of SARS-CoV-2 comprises one or more of the group consisting of the spike (S) protein, the membrane (M) protein, nucleocapsid (N) protein, and envelope (E) protein. In some embodiments, the SARS-CoV-2 antigen comprises or further comprises a non-structural protein of SARS-CoV-2 or a fragment thereof. The nucleotide sequence of a representative SARS-CoV-2 isolate (Wuhan-Hu-1) is set forth as GenBank No. MN908947.3 (Wu et al., Nature, 579:265-269, 2020).

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 55. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 55 shown below (underlined sequence indicating the receptor-binding motif (RBM) within the receptor binding domain (RBD) from Thr333-Gly526, bolded). In some embodiments, the viral antigen or immunogen comprises an RBD-Trimer™, for example, a SARS-CoV-2 RBD sequence linked to any of SEQ ID Nos: 67-80.

        10        20        30        40        50        60  MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFS          70        80        90       100       110       120  NVTWFHAIHVSGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIV         130       140       150       160       170       180  NNATNVVIKVCEFQFCNDPFLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLE         190       200       210       220       230       240  GKQGNFKNLREFVFKNIDGYFKIYSKHTPINLVRDLPQGFSALEPLVDLPIGINITRFQT         250       260       270       280       290       300  LLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENGTITDAVDCALDPLSETK         310       320       330       340       350       360  CTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAWNRKRISN         370       380       390       400       410       420  CVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIAD         430       440       450       460       470       480  YNYKLPDDFTGCVIAW NSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPC          490       500       510       520       530       540  NGVEGFNCYFPLQSYGFQPTNGVGYQPYR VVVLSFELLHAPATVCGPKKSTNLVKNKCVN         550       560       570       580       590       600  FNFNGLTGTGVLTESNKKFLPFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITP         610       620       630       640       650       660  GTNTSNQVAVLYQDVNCTEVPVAIHADQLTPTWRVYSTGSNVFQTRAGCLIGAEHVNNSY         670       680       690       700       710       720  ECDIPIGAGICASYQTQTNSPRRARSVASQSIIAYTMSLGAENSVAYSNNSIAIPTNFTI         730       740       750       760       770       780  SVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVEQDKNTQE         790       800       810       820       830 840  VFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSFIEDLLFNKVTLADAGFIKQYGDC         850       860       870       880       890       900  LGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGAALQIPFAM         910       920       930       940       950       960  QMAYRFNGIGVTQNVLYENQKLIANQFNSAIGKIQDSLSSTASALGKLQDVVNQNAQALN         970       980       990      1000      1010      1020  TLVKQLSSNFGAISSVLNDILSRLDKVEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRA        1030      1040      1050      1060      1070      1080  SANLAATKMSECVLGQSKRVDFCGKGYHLMSFPQSAPHGVVFLHVTYVPAQEKNFTTAPA        1090      1100      1110      1120      1130      1140  ICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSGNCDVVIGIVNNTVYDP        1150      1160      1170      1180      1190      1200  LQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLNESLIDL        1210      1220      1230      1240      1250      1260  QELGKYEQYIKWPWYIWLGFIAGLIAIVMVTIMLCCMTSCCSCLKGCCSCGSCCKFDEDD        1270  SEPVLKGVKLHYT

In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of the original Wuhan-Hu-1 coronavirus (e.g., NC_045512). In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.526 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a Cluster 5 (ΔFVI-spike) virus. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.1.7 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.1.207 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.1.317 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.1.318 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the P.1 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.351 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.429/CAL.20C lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.525 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.526 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.617 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.617.2 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.618 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.620 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the P.2 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the P.3 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.1.143 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the A.23.1 lineage. In some embodiments, the viral antigen or immunogen comprises a sequence of the spike glycoprotein of a virus in the B.1.617 lineage. In some embodiments, the viral antigen or immunogen comprises sequences derived from the spike glycoproteins of any two or more viruses, in any suitable combination, selected from the group consisting of Wuhan-Hu-1, a virus in the B.1.526 lineage, a virus in the B.1.1.7 lineage, a virus in the P.1 lineage, a virus in the B.1.351 lineage, a virus in the P.2 lineage, a virus in the B.1.1.143 lineage, a virus in the A.23.1 lineage, and a virus in the B.1.617 lineage.

In some embodiments, the viral antigen or immunogen comprises E484K and/or S477N, e.g., as in a B.1.526 variant. In some embodiments, the viral antigen or immunogen comprises Δ400-402 (ΔFVI), e.g., as in a Cluster 5 (ΔFVI-spike) variant. In some embodiments, the viral antigen or immunogen comprises Δ69-70 (ΔHV), Δ144 (ΔY), N501Y, A570D, D614G, P681H, T716I, S982A, and/or D1118H, e.g., as in a B.1.1.7 variant. In some embodiments, the viral antigen or immunogen comprises P681H, e.g., as in a B.1.1.207 variant. In some embodiments, the viral antigen or immunogen comprises L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I, and/or V1176F, e.g., as in a P.1 variant. In some embodiments, the viral antigen or immunogen comprises E484K, e.g., as in a P.2 variant. In some embodiments, the viral antigen or immunogen comprises E484K and/or N501Y, e.g., as in a P.3 variant. In some embodiments, the viral antigen or immunogen comprises L18F, D80A, D215G, A242-244 (ΔLAL), R246I, K417N, E484K, N501Y, D614G, and/or A701V, e.g., as in a B.1.351 variant. In some embodiments, the viral antigen or immunogen comprises S13I, W152C, and/or L452R, e.g., as in a B.1.429/CAL.20C variant. In some embodiments, the viral antigen or immunogen comprises Δ69-70 (ΔHV), E484K, and/or F888L, e.g., as in a B.1.525 variant. In some embodiments, the viral antigen or immunogen comprises G142D, L452R, E484Q, and/or P681R, e.g., as in a B.1.617 variant. In some embodiments, the viral antigen or immunogen comprises G142D, L452R, and/or P681R, e.g., as in a B.1.617.2 variant. In some embodiments, the viral antigen or immunogen comprises E484K, e.g., as in a B.1.618 variant. In some embodiments, the viral antigen or immunogen may comprise a fusion polypeptide (protomer) comprising any one or more of the aforementioned mutations in any suitable combination. In some embodiments, the viral antigen or immunogen may comprise a trimer of three fusion polypeptides, and any of the three protomer fusion polypeptides may comprise any one or more of the aforementioned mutations in any suitable combination. In some embodiments, two or all three of the three protomer fusion polypeptides forming a trimer may comprise different mutations and/or different combinations of mutations in each protomer. In some embodiments, the viral antigen or immunogen may comprise a mixture of trimers, and each trimer may comprise different mutations and/or different combinations of mutations.

In some embodiments, the viral antigen or immunogen comprises any one, two, three, four, five or more of the mutations selected from the group consisting of mutations (e.g., substitution(s), deletion(s) and/or insertion(s)) at amino acid positions 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 of SEQ ID NO: 55. In some embodiments, the viral antigen or immunogen comprises any one, two, three, four, five, six, seven, eight, or all of the mutations selected from the group consisting of mutations (e.g., substitution(s), deletion(s) and/or insertion(s)) at amino acid positions 440, 452, 477, 484, 501, 614, 655, 681, and 701. In some embodiments, the viral antigen or immunogen comprises a chimeric polypeptide comprising sequences from different viruses, such as one or more mutations from a first variant of a coronavirus and one or more mutations from a second variant of the coronavirus that is different from the first variant. In some embodiments, such a chimeric viral antigen or immunogen (or a combination of chimeric viral antigens or immunogens) may be used to elicit a broad immune response against both the first and second variants of the coronavirus.

In some embodiments, the viral antigen or immunogen comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, A144 (ΔY), W152C, R190S, D215G, A242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F. In some embodiments, the viral antigen or immunogen comprises any one, two, three, four, five or more of the mutations selected from the group consisting of N440K, L452R, S477G, S477N, E484K, E484Q, N501Y, D614G, H655Y, P681H, P681R, and A701V.

In some embodiments, the SARS-CoV-2 antigen comprises a truncated, S protein devoid of signal peptide, transmembrane and cytoplasmic domains of a full length S protein. In some embodiments, the SARS-CoV-2 antigen is a recombinant protein, while in other embodiments, the SARS-CoV-2 antigen is purified from virions. In some preferred embodiments, the SARS-CoV-2 antigen is an isolated antigen.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 27. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 27, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 27 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, A69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 28. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 28, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 28 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, A400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 29. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 29, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 29 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, A242-244 (ΔLAL), R246I, A400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 30. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 30, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 30 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, A242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 31. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 31, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 31 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, A400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 32. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 32, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 32 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 33. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 33, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 33 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 34. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 34, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 34 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 35. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 35, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 35 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 36. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 36, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 36 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 37. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 37, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 37 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 38. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 38, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 38 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 39. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 39, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 39 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 40. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 40, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 40 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 41. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 41, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 41 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 42. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 42, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 42 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 43. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 43, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 43 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 44. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 44, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 44 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 45. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 45, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 45 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 46. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 46, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 46 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 47. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 47, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 47 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 48. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 48, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 48 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 49. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 49, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 49 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 50. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 50, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 50 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 51. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 51, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 51 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 52. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 52.

In some embodiments, the viral antigen or immunogen comprises a signal peptide. In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 53. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 53. In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 54. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 54.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 55. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 55, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176. In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 55 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 56. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 56, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions selected from the group consisting of 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and 1176 (amino acid positions with respect to SEQ ID NO: 55). In some embodiments, the viral antigen or immunogen comprises a variant of SEQ ID NO: 56 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 57. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 57, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 57.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 58. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 58, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 58.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 59. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 59. In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 60. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 60.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 61. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 61, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 61.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 62. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 62, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 62.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 63. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 63, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 63.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 64. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 64, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 64.

In some embodiments, the viral antigen or immunogen comprises the sequence set forth in SEQ ID NO: 65. In some embodiments, the viral antigen or immunogen comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 65, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 65.

In some embodiments, the viral antigen or immunogen does not comprise a transmembrane domain such as SEQ ID NO: 66 or a portion thereof. In some embodiments, the coronavirus viral antigen or immunogen comprises an S protein peptide that is soluble. In some embodiments, the soluble S protein peptide lacks a TM domain peptide and a CP domain peptide. In some embodiments, the soluble S protein peptide does not bind to a lipid bilayer, such as a membrane or viral envelope.

In some embodiments, the S protein peptide is produced from a nucleic acid sequence that has been codon optimized. In some embodiments, the S protein peptide is produced from a nucleic acid sequence that has not been codon optimized.

In some embodiments, the viral antigen or immunogen as referred to herein can include recombinant polypeptides or fusion peptides comprising said viral antigen or immunogen. The terms viral antigen or immunogen may be used to refer to proteins comprising a coronavirus viral antigen or immunogen. In certain cases, the coronavirus viral antigen or immunogen is a coronavirus protein peptide as provided herein.

II. Recombinant Peptides and Proteins

It is contemplated that the coronavirus viral antigens and immunogens provided herein, e.g., S protein peptides (see, Section I), can be combined, e.g., linked, to other proteins or peptides to form recombinant polypeptides, including fusion peptides. In some embodiments, individual recombinant polypeptides (e.g., monomers) provided herein associate to form multimers, e.g., trimers, of recombinant polypeptides. In some embodiments, association of the individual recombinant polypeptide monomers occurs via covalent interactions. In some embodiments, association of the individual recombinant polypeptide monomers occurs via non-covalent interactions. In some embodiments, the interaction, e.g., covalent or non-covalent, is effected by the protein or peptide to which the coronavirus viral antigen or immunogen, e.g., S protein peptide, is linked. In some embodiments, for example when the coronavirus viral antigen or immunogen is an S protein peptide as described herein, the protein or peptide to which it will be linked can be selected such that the native homotrimeric structure of the glycoprotein is preserved. This can be advantageous for evoking a strong and effective immunogenic response to the S protein peptide. For example, preservation and/or maintenance of the native conformation of the coronavirus viral antigens or immunogens (e.g., S protein peptide) may improve or allow access to antigenic sites capable to generating an immune response. In some cases, the recombinant polypeptide comprising an S protein peptide described herein, e.g., see Section I, is referred to herein alternatively as a recombinant S antigen, recombinant S immunogen, or a recombinant S protein.

It is further contemplated that in some cases, the recombinant polypeptides or multimerized recombinant polypeptides thereof aggregate or can be aggregated to form a protein or a complex comprising a plurality of coronavirus viral antigen and/or immunogen recombinant polypeptides. Formation of such proteins may be advantageous for generating a strong and effective immunogenic response to the coronavirus viral antigens and/or immunogens. For instance, formation of a protein comprising a plurality of recombinant polypeptides, and thus a plurality of coronavirus viral antigens, e.g., coronavirus S protein peptides, may preserve the tertiary and/or quaternary structures of the viral antigen, allowing an immune response to be mounted against the native structure. In some cases, the aggregation may confer structural stability of the coronavirus viral antigen or immunogen, which in turn can afford access to potentially antigenic sites capable of promoting an immune response.

1. Fusion Peptides and Recombinant Polypeptides

In some embodiments, the coronavirus viral antigen or immunogen can be linked at their C-terminus (C-terminal linkage) to a trimerization domain to promote trimerization of the monomers. In some embodiments, the trimerization stabilizes the membrane proximal aspect of the coronavirus viral antigen or immunogen, e.g., coronavirus S protein peptide, in a trimeric configuration.

Non-limiting examples of exogenous multimerization domains that promote stable trimers of soluble recombinant proteins include: the GCN4 leucine zipper (Harbury et al. 1993 Science 262:1401-1407), the trimerization motif from the lung surfactant protein (Hoppe et al. 1994 FEBS Lett 344:191-195), collagen (McAlinden et al. 2003 J Biol Chem 278:42200-42207), and the phage T4 fibritin Foldon (Miroshnikov et al. 1998 Protein Eng 11:329-414), any of which can be linked to a coronavirus viral antigen or immunogen described herein (e.g., by linkage to the C-terminus of an S peptide) to promote trimerization of the recombinant viral antigen or immunogen. See also U.S. Pat. Nos. 7,268,116, 7,666,837, 7,691,815, 10,618,949, 10,906,944, and 10,960,070, and US 2020/0009244, which are incorporated herein by reference in their entireties for all purposes.

In some embodiments, one or more peptide linkers (such as a gly-ser linker, for example, a 10 amino acid glycine-serine peptide linker) can be used to link the recombinant viral antigen or immunogen to the multimerization domain. The trimer can include any of the stabilizing mutations provided herein (or combinations thereof) as long as the recombinant viral antigen or immunogen trimer retains the desired properties (e.g., the prefusion conformation). In some embodiments, the recombinant polypeptide or the fusion protein comprises a first sequence set forth in any of SEQ ID NOs: 27-66 linked to a second sequence set forth in any of SEQ ID NOs: 67-80, wherein the C terminus of the first sequence is directly linked to the N terminus of the second sequence. In some embodiments, the recombinant polypeptide or the fusion protein comprises a first sequence set forth in any of SEQ ID NOs: 27-66 linked to a second sequence set forth in any of SEQ ID NOs: 67-80, wherein the C terminus of the first sequence is indirectly linked to the N terminus of the second sequence, e.g. through a linker. In some embodiments, the linker comprises a sequence comprising glycine-X-Y repeats.

To be therapeutically feasible, a desired trimerizing protein moiety for biologic drug designs should satisfy the following criteria. Ideally it should be part of a naturally secreted protein, like immunoglobulin Fc, that is also abundant (non-toxic) in the circulation, human in origin (lack of immunogenicity), relatively stable (long half-life) and capable of efficient self-trimerization which is strengthened by inter-chain covalent disulfide bonds so the trimerized coronavirus viral antigens or immunogens are structurally stable.

Collagen is a family of fibrous proteins that are the major components of the extracellular matrix. It is the most abundant protein in mammals, constituting nearly 25% of the total protein in the body. Collagen plays a major structural role in the formation of bone, tendon, skin, cornea, cartilage, blood vessels, and teeth. The fibrillar types of collagen I, II, III, IV, V, and XI are all synthesized as larger trimeric precursors, called procollagens, in which the central uninterrupted triple-helical domain consisting of hundreds of “G-X-Y” repeats (or glycine repeats) is flanked by non-collagenous domains (NC), the N-propeptide and the C-propeptide. Both the C- and N-terminal extensions are processed proteolytically upon secretion of the procollagen, an event that triggers the assembly of the mature protein into collagen fibrils which forms an insoluble cell matrix. BMP-1 is a protease that recognizes a specific peptide sequence of procollagen near the junction between the glycine repeats and the C-prodomain of collagens and is responsible for the removal of the propeptide. The shed trimeric C-propeptide of type I collagen is found in human sera of normal adults at a concentration in the range of 50-300 ng/mL, with children having a much higher level which is indicative of active bone formation. In people with familial high serum concentration of C-propeptide of type I collagen, the level could reach as high as 1-6 μg/mL with no apparent abnormality, suggesting the C-propeptide is not toxic. Structural study of the trimeric C-propeptide of collagen suggested that it is a tri-lobed structure with all three subunits coming together in a junction region near their N-termini to connect to the rest of the procollagen molecule. Such geometry in projecting proteins to be fused in one direction is similar to that of Fc dimer.

Type I, IV, V and XI collagens are mainly assembled into heterotrimeric forms consisting of either two α-1 chains and one α-2 chain (for Type I, IV, V), or three different a chains (for Type XI), which are highly homologous in sequence. The type II and III collagens are both homotrimers of α-1 chain. For type I collagen, the most abundant form of collagen, stable α(I) homotrimer is also formed and is present at variable levels in different tissues. Most of these collagen C-propeptide chains can self-assemble into homotrimers, when over-expressed alone in a cell. Although the N-propeptide domains are synthesized first, molecular assembly into trimeric collagen begins with the in-register association of the C-propeptides. It is believed the C-propeptide complex is stabilized by the formation of interchain disulfide bonds, but the necessity of disulfide bond formation for proper chain registration is not clear. The triple helix of the glycine repeats and is then propagated from the associated C-termini to the N-termini in a zipper-like manner. This knowledge has led to the creation of non-natural types of collagen matrix by swapping the C-propeptides of different collagen chains using recombinant DNA technology. Non-collagenous proteins, such as cytokines and growth factors, also have been fused to the N-termini of either procollagens or mature collagens to allow new collagen matrix formation, which is intended to allow slow release of the noncollagenous proteins from the cell matrix. However, under both circumstances, the C-propeptides are required to be cleaved before recombinant collagen fibril assembly into an insoluble cell matrix.

Although other protein trimerization domains, such as those from GCN4 from yeast fibritin from bacteria phage T4 and aspartate transcarbamoylase of Escherichia coli, have been described previously to allow trimerization of heterologous proteins, none of these trimerizing proteins are human in nature, nor are they naturally secreted proteins. As such, any trimeric fusion proteins would have to be made intracellularly, which not only may fold incorrectly for naturally secreted proteins such as soluble receptors, but also make purification of such fusion proteins from thousands of other intracellular proteins difficult. Moreover, the fatal drawback of using such non-human protein trimerization domains (e.g. from yeast, bacteria phage and bacteria) for trimeric biologic drug design is their presumed immunogenicity in the human body, rendering such fusion proteins ineffective shortly after injecting them into the human body.

The use of collagen in a recombinant polypeptide as described herein thus has many advantages, including: (1) collagen is the most abundant protein secreted in the body of a mammal, constituting nearly 25% of the total proteins in the body; (2) the major forms of collagen naturally occur as trimeric helixes, with their globular C-propeptides being responsible for the initiating of trimerization; (3) the trimeric C-propeptide of collagen proteolytically released from the mature collagen is found naturally at sub microgram/mL level in the blood of mammals and is not known to be toxic to the body; (4) the linear triple helical region of collagen can be included as a linker with predicted 2.9 Å spacing per residue, or excluded as part of the fusion protein so the distance between a protein to be trimerized and the C-propeptide of collagen can be precisely adjusted to achieve an optimal biological activity; (5) the recognition site of BMP1 which cleaves the C-propeptide off the pro-collagen can be mutated or deleted to prevent the disruption of a trimeric fusion protein; (6) the C-propeptide domain self-trimerizes via disulfide bonds and it provides a universal affinity tag, which can be used for purification of any secreted fusion proteins created. In some embodiments, the C-propeptide of collagen to which the coronavirus viral antigen and immunogen, e.g., S protein peptide, enables the recombinant production of soluble, covalently-linked homotrimeric fusion proteins.

In some embodiments, the coronavirus viral antigen or immunogen is linked to a C-terminal propeptide of collagen to form a recombinant polypeptide. In some embodiments, the C-terminal propeptides of the recombinant polypeptides form inter-polypeptide disulfide bonds. In some embodiments, the recombinant proteins form trimers. In some embodiments, the coronavirus viral antigen or immunogen is an S protein peptide as described in Section I.

For example, a fusion polypeptide comprising a signal peptide MFVFLVLLPLVSS (SEQ ID NO: 54) on the N-terminus of the fusion polypeptide in SEQ ID NO: 1 may be produced and trimerized via inter-polypeptide disulfide bonds (Cys residues that may form inter-polypeptide disulfide bonds are bolded).

        10        20        30        40        50        60  MFVFLVLLPLVSSQCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFS          70        80        90       100       110       120  NVTWFHAIHVSGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQSLLIV         130       140       150       160       170       180  NNATNVVIKVCEFQFCNDPFLGVYYHKNNKSWMESEFRVYSSANNCTFEYVSQPFLMDLE         190       200       210       220       230       240  GKQGNFKNLREFVFKNIDGYFKIYSKHTPINLVRDLPQGFSALEPLVDLPIGINITRFQT         250       260       270       280       290       300  LLALHRSYLTPGDSSSGWTAGAAAYYVGYLQPRTFLLKYNENGTITDAVDCALDPLSETK         310       320       330       340       350       360  CTLKSFTVEKGIYQTSNFRVQPTESIVRFPNITNLCPFGEVFNATRFASVYAWNRKRISN         370       380       390       400       410       420  CVADYSVLYNSASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIAD         430       440       450       460       470       480  YNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGSTPC         490       500       510       520       530       540  NGVEGFNCYFPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCGPKKSTNLVKNKCVN         550       560       570       580       590       600  FNFNGLTGTGVLTESNKKFLPFQQFGRDIADTTDAVRDPQTLEILDITPCSFGGVSVITP         610       620       630       640       650       660  GTNTSNQVAVLYQDVNCTEVPVAIHADQLTPTWRVYSTGSNVFQTRAGCLIGAEHVNNSY         670       680       690       700       710       720  ECDIPIGAGICASYQTQTNSPRRARSVASQSIIAYTMSLGAENSVAYSNNSIAIPTNFTI         730       740       750       760       770       780  SVTTEILPVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVEQDKNTQE         790       800       810       820       830       840  VFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSFIEDLLFNKVTLADAGFIKQYGDC         850       860       870       880       890       900  LGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAGTITSGWTFGAGAALQIPFAM         910       920       930       940       950       960  QMAYRFNGIGVTQNVLYENQKLIANQFNSAIGKIQDSLSSTASALGKLQDVVNQNAQALN         970       980       990      1000       1010     1020  TLVKQLSSNFGAISSVLNDILSRLDKVEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRA        1030      1040      1050      1060      1070      1080  SANLAATKMSECVLGQSKRVDFCGKGYHLMSFPQSAPHGVVFLHVTYVPAQEKNFTTAPA        1090      1100      1110      1120      1130      1140  ICHDGKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSGNCDVVIGIVNNTVYDP        1150      1160      1170      1180      1190      1200  LQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRLNEVAKNLNESLIDL        1210      1220      1230      1240      1250      1260  QELGKYEQYIKRSNGLPGPIGPPGPRGRTGDAGPVGPPGPPGPPGPPGPPSAGFDFSFLP        1270      1280      1290      1300      1310      1320  QPPQEKAHDGGRYYRANDANVVRDRDLEVDTTLKSLSQQIENIRSPEGSRKNPARTCRDL        1330      1340      1350      1360      1370      1380  KMCHSDWKSGEYWIDPNQGCNLDAIKVFCNMETGETCVYPTQPSVAQKNWYISKNPKDKR        1390      1400      1410      1420      1430      1440  HVWFGESMTDGFQFEYGGQGSDPADVAIQLTFLRLMSTEASQNITYHCKNSVAYMDQQTG        1450      1460      1470      1480      1490      1500  NLKKALLLQGSNEIEIRAEGNSRFTYSVTVDGCTSHTGAWGKTVIEYKTTKTSRLPIIDV        1510      1520  APLDVGAPDQEFGFDVGPVCFL

In some embodiments, the inter-polypeptide disulfide bonds may comprise one or more or all of Cys15-136, Cys131-166, Cys291-301, Cys379-432, Cys336-361, Cys391-525, Cys480-488, Cys538-590, Cys617-649, Cys662-671, Cys743-749, Cys738-760, Cys840-851, Cys1032-1043, and Cys1082-1126, in any suitable combination. In some embodiments, the fusion polypeptide in the trimer may comprise one or more glycosylation sites (e.g., Asn-linked), for example, at one or more or all of Asn residues at 17, 61, 122, 149, 165, 234, 282, 331, 343, 603, 616, 657, 709, 717, 801, 1074, 1098, and 1134, in any suitable combination.

In some embodiments, the C-terminal propeptide is of human collagen. In some embodiments, the C-terminal propeptide comprises a C-terminal polypeptide of proα1(I), proα1(II), proα1(III), proα1(V), proα1(XI), proα2(I), proα2(V), proα2(XI), or proα3(XI), or a fragment thereof. In some embodiments, the C-terminal propeptide is or comprises a C-terminal polypeptide of proα1(I).

In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 67. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 67. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 68. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 68. In some embodiments, the C-terminal propeptide is or is the amino acid sequence set forth by SEQ ID NO: 69. In some embodiments, the C-terminal propeptide exhibits an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 69. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 70. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 70. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 71. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 71.

In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 72. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 72. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 73. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 73. In some embodiments, the C-terminal propeptide is or is the amino acid sequence set forth by SEQ ID NO: 74. In some embodiments, the C-terminal propeptide exhibits an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 74. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 75. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 75. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 76. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 76.

In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 77. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 77. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 78. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 78. In some embodiments, the C-terminal propeptide is or is the amino acid sequence set forth by SEQ ID NO: 79. In some embodiments, the C-terminal propeptide exhibits an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 79. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence set forth by SEQ ID NO: 80. In some embodiments, the C-terminal propeptide is an amino acid sequence having at least or about 85%, 90%, 92%, 95%, or 97% sequence identity to SEQ ID NO: 80.

In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence of a collagen trimerization domain (e.g., C-propeptide of human α1(I) collagen) with an aspartic acid (D) to asparagine (N) substitution in the BMP-1 site, for instance, as shown in SEQ ID NO: 68 where RAD is mutated to RAN. In some embodiments, the C-terminal propeptide is or comprises the amino acid sequence of a collagen trimerization domain (e.g., C-propeptide of human α1(I) collagen) with an alanine (A) to asparagine (N) substitution in the BMP-1 site, for instance, as shown in SEQ ID NO: 69 where RAD is mutated to RND. In some embodiments, the C-terminal propeptide herein may comprise a mutated BMP-1 site, e.g., RSAN instead of DDAN. In some embodiments, the C-terminal propeptide herein may comprise a BMP-1 site, e.g., a sequence (such as SEQ ID NO: 68 or 69) comprising the RAD (e.g., RADDAN) sequence instead of RAN (e.g., RANDAN) or RND (e.g., RNDDAN) may be used in a fusion polypeptide disclosed herein. For instance, SEQ ID NO: 27 (underlined) or a fragment, variant or mutant thereof may be directly or indirectly linked to SEQ ID NO: 67 (italicized) or a fragment, variant or mutant there, e.g., to form the following fusion protein:

QCVNLTTRTQLPPAYTNSFTRGVYYPDKVFRSSVLHSTQDLFLPFFSNVTW FHAIHVSGTNGTKRFDNPVLPFNDGVYFASTEKSNIIRGWIFGTTLDSKTQ SLLIVNNATNVVIKVCEFQFCNDPFLGVYYHKNNKSWMESEFRVYSSANNC TFEYVSQPFLMDLEGKQGNFKNLREFVFKNIDGYFKIYSKHTPINLVRDLP QGFSALEPLVDLPIGINITRFQTLLALHRSYLTPGDSSSGWTAGAAAYYVG YLQPRTFLLKYNENGTITDAVDCALDPLSETKCTLKSFTVEKGIYQTSNFR VQPTESIVRFPNITNLCPFGEVFNATRFASVYAWNRKRISNCVADYSVLYN SASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADY NYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEI YQAGSTPCNGVEGFNCYFPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPAT VCGPKKSTNLVKNKCVNFNFNGLTGTGVLTESNKKFLPFQQFGRDIADTTD AVRDPQTLEILDITPCSFGGVSVITPGTNTSNQVAVLYQDVNCTEVPVAIH ADQLTPTWRVYSTGSNVFQTRAGCLIGAEHVNNSYECDIPIGAGICASYQT QTNSPRRARSVASQSIIAYTMSLGAENSVAYSNNSIAIPTNFTISVTTEIL PVSMTKTSVDCTMYICGDSTECSNLLLQYGSFCTQLNRALTGIAVEQDKNT QEVFAQVKQIYKTPPIKDFGGFNFSQILPDPSKPSKRSFIEDLLFNKVTLA DAGFIKQYGDCLGDIAARDLICAQKFNGLTVLPPLLTDEMIAQYTSALLAG TITSGWTFGAGAALQIPFAMQMAYRFNGIGVTQNVLYENQKLIANQFNSAI GKIQDSLSSTASALGKLQDVVNQNAQALNTLVKQLSSNFGAISSVLNDILS RLDKVEAEVQIDRLITGRLQSLQTYVTQQLIRAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFPQSAPHGVVFLHVTYVPAQEKNFTTAPAICHD GKAHFPREGVFVSNGTHWFVTQRNFYEPQIITTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKYFKNHTSPDVDLGDISGINASVVNIQKEIDRL NEVAKNLNESLIDLQELGKYEQ YIKRSANVVRDRDLEVDTTLKSLSQQIEN IRSPEGSRKNPARTCRDLKMCHSDWKSGEYWIDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYISKNPKDKRHVWFGESMTDGFQFEYGGQGSDPA DVAIQLTFLRLMSTEASQNITYHCKNSVAYMDQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTSHTGAWGKTVIEYKTTKTSRLPIIDVAPLDVG APDQEFGFDVGPVCFL

In some embodiments, the C-terminal propeptide is or comprises an amino acid sequence that is a fragment of any of SEQ ID NOs: 67-80.

In some embodiments, the C-terminal propeptide can comprise a sequence comprising glycine-X-Y repeats, wherein X and Y are independently any amino acid, or an amino acid sequence at least 85%, 90%, 92%, 95%, or 97% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides. In some embodiments, X and Y are independently proline or hydroxyproline.

In some cases where an S protein peptide is linked to the C-terminal propeptide to form the recombinant polypeptide, the recombinant polypeptides form a trimer resulting in a homotrimer of S protein peptides. In some embodiments, the S protein peptides of the trimerized recombinant polypetides are in a prefusion conformation. In some embodiments, the S protein peptides of the trimerized recombinant polypetides are in a postfusion conformation. In some embodiments, the confirmation state allows for access to different antigenic sites on the S protein peptides. In some embodiments, the antigenic sites are epitopes, such as linear epitopes or conformational epitopes. An advantage of having a trimerized recombinant polypeptides as described is that an immune response can be mounted against a variety of potential and diverse antigenic sites.

In some embodiments, trimerized recombinant polypeptides include individual recombinant polypeptides comprising the same viral antigen or immunogen. In some embodiments, trimerized recombinant polypeptides include individual recombinant polypeptides each comprising a different viral antigen or immunogen from the other recombinant polypeptides. In some embodiments, trimerized recombinant polypeptides include individual recombinant polypeptides wherein one of the individual recombinant polypeptides comprises a viral antigen or immunogen different from the other recombinant polypeptides. In some embodiments, trimerized recombinant polypeptides include individual recombinant polypeptides wherein two of the individual recombinant polypeptides comprise the same viral antigen or immunogen, and the viral antigen or immunogen is different from the viral antigen or immunogen comprised in the remaining recombinant polypeptide.

In some embodiments, the recombinant polypeptide comprises any coronavirus viral antigen or immunogen described in Section I. In some embodiments, the recombinant polypeptide comprises any coronavirus viral antigen or immunogen described in Section I linked, as described herein, to the C-terminal propeptide of collagen as described herein.

In some embodiments, the immunogen comprises a recombinant SARS-CoV or SARS-CoV-2 S ectodomain trimer comprising protomers comprising one or more (such as two, for example two consecutive) proline substitutions at or near the boundary between a HR1 domain and a central helix domain that stabilize the S ectodomain trimer in the prefusion conformation. In some such embodiments, the one or more (such as two, for example two consecutive) proline substitutions that stabilize the S ectodomain in the prefusion conformation are located between a position 15 amino acids N-terminal of a C-terminal residue of the HR1 and a position 5 amino acids C-terminal of a N-terminal residue of the central helix.

In some embodiments, the one or more (such as two, for example two consecutive) proline substitutions stabilize the coronavirus (e.g., SARS-CoV or SARS-CoV-2) S ectodomain trimer in the prefusion conformation. In some embodiments, the SARS-CoV-2 S protein peptide comprises 986K/987V to 986P/987P mutations.

In some embodiments, the recombinant coronavirus (e.g., SARS-CoV or SARS-CoV-2) S ectodomain trimer stabilized in the prefusion conformation comprises single-chain S ectodomain protomers comprising mutations to the S1/S2 and/or S2′ protease cleavage sites to prevent protease cleavage at these sites. In some embodiments, the SARS-CoV-2 S protein peptide comprises a 685R to 685A mutation. Exemplary protease cleavage sites for various viruses are shown below:

S1/S2, Coronavirus S1/S2, site site 2 S2* 2019-nCoV SPR 

AR↓SVAS IAY↓TMS SKPSKR↓SF CoV-ZX21 TASILR↓STGQ IAY↓TMS SKPSKR↓SF Bat-AC45 TASILR↓STGQ IAY↓TMS SKPSKR↓SF SARS-CoV TVSLLR↓STGQ IAY↓TMS LKPTKR↓SF BM48-31 SSTLVR↓SGG 

LAY↓TMS LKPTKR↓SF HKU9-1 ADSLPR↓LQLV VNY↓DPL GATTYR↓SA MERS-CoV TPRSCR↓SVPG GSRSAR↓SA HKU1

PRKRR↓SISA CGSSSR↓SF HCoV-OC43 KNRPSR↓GAITT SKASSR↓SA HCoV-229E IAVQ 

R↓NVSYD SRVAGR↓SA HCoV-NL63 IPVRPR↓NSSDN SRIAGR↓SA

indicates data missing or illegible when filed

In some embodiments, the protomers of the recombinant coronavirus (e.g., SARS-CoV or SARS-CoV-2) S ectodomain trimer stabilized in the prefusion conformation by the one or more proline substitutions (such as 986P/987P substitutions) comprises additional modifications for stabilization in the prefusion conformation, such as a mutation at a protease cleavage site to prevent protease cleavage.

With reference to the SARS-CoV-2 S protein sequence provided as SEQ ID NO: 55, the ectodomain comprises a signal peptide (SP), which is removed during cellular processing; an N-terminal domain (NTD); a receptor binding domain (RBD); one or more S1/S2 cleavage sites; a fusion peptide (FP); internal fusion peptide (IFP); heptad repeat 1/2 (HR1/2), and the transmembrane domain (TM). Exemplary sources of the sequence can be found at ncbi.nlm.nih.gov/nuccore/MN908947.3, ncbi.nlm.nih.gov/nuccore/MN908947, ncbi.nlm.nih.gov/nuccore/MN908947.2. Additional sequences can be found at ncbi.nlm.nih.gov/genbank/sars-cov-2-seqs/, including the pneumonia virus isolate Wuhan-Hu-1, complete genome.

In some embodiments, the protomers of the prefusion-stabilized SARS-CoV-2 S ectodomain trimer can have a C-terminal residue (which can be linked to a trimerization domain, or a transmembrane domain, for example) of the C-terminal residue of the NTD, the RBD, S1 (at either the S1/S2 site 1, or S1/S2 site 2), FP, IFP, HR1, HR2, or the ectodomain. The position numbering of the S protein may vary between SARS-CoV stains, but the sequences can be aligned to determine relevant structural domains and cleavage sites. It will be appreciated that a few residues (such as up to 10) on the N and C-terminal ends of any of the ectodomain fragment can be removed or modified in the disclosed immunogens without decreasing the utility of the S ectodomain trimer as an immunogen.

In some embodiments, the recombinant polypeptide is or comprises an NTD peptide of SARS-CoV or SARS-CoV-2 S protein. In some embodiments, the recombinant polypeptide is or comprises an RBD peptide of SARS-CoV or SARS-CoV-2 S protein. In some embodiments, the recombinant polypeptide is or comprises an NTD peptide and an RBD peptide of SARS-CoV or SARS-CoV-2 S protein. In some embodiments, the recombinant polypeptide is or comprises an S1 domain peptide of SARS-CoV or SARS-CoV-2 S protein. In some embodiments, the recombinant polypeptide is or comprises an S2 domain peptide of SARS-CoV or SARS-CoV-2 S protein.

An exemplary SARS-CoV-1 S recombinant polypeptide without a signal peptide is provided in SEQ ID NO: 26 (1491 aa):

        10         20         30         40         50         60  SDLDRCTTFD DVQAPNYTQH TSSMRGVYYP DEIFRSDTLY LTQDLFLPFY SNVTGFHTIN          70         80         90        100        110        120  HTFDNPVIPF KDGIYFAATE KSNVVRGWVF GSTMNNKSQS VIIINNSTNV VIRACNFELC         130        140        150        160        170        180  DNPFFAVSKP MGTQTHTMIF DNAFNCTFEY ISDAFSLDVS EKSGNFKHLR EFVFKNKDGF         190        200        210        220        230        240  LYVYKGYQPI DVVRDLPSGF NTLKPIFKLP LGINITNFRA ILTAFLPAQD TWGTSAAAYF         250        260        270        280        290        300  VGYLKPTTFM LKYDENGTIT DAVDCSQNPL AELKCSVKSF EIDKGIYQTS NFRVVPSRDV         310        320        330        340        350        360  VRFPNITNLC PFGEVFNATK FPSVYAWERK RISNCVADYS VLYNSTFFST FKCYGVSATK         370        380        390        400        410        420  LNDLCFSNVY ADSFVVKGDD VRQIAPGQTG VIADYNYKLP DDFMGCVLAW NTRNIDATST         430        440        450        460        470        480  GNYNYKYRYL RHGKLRPFER DISNVPFSPD GKPCTPPALN CYWPLNDYGF YTTTGIGYQP         490        500        510        520        530        540  YRVVVLSFEL LNAPATVCGP KLSTDLIKNQ CVNFNFNGLT GTGVLTPSSK RFQPFQQFGR         550        560        570        580        590        600  DVSDFTDSVR DPKTSEILDI SPCSFGGVSV ITPGTNASSE VAVLYQDVNC TDVSTAIHAD         610        620        630        640        650        660  QLTPAWRIYS TGNNVFQTQA GCLIGAEHVD TSYECDIPIG AGICASYHTV SLLRSTSQKS         670        680        690        700        710        720  IVAYTMSLGA DSSIAYSNNT IAIPTNFSIS ITTEVMPVSM AKTSVDCNMY ICGDSTECAN         730        740        750        760        770        780  LLLQYGSFCT QLNRALSGIA AEQDRNTREV FAQVKQMYKT PTLKDFGGFN FSQILPDPLK         790        800        810        820        830        840  PTKRSFIEDL LFNKVTLADA GFMKQYGECL GDINARDLIC AQKFNGLTVL PPLLTDDMIA         850        860        870        880        890        900  AYTAALVSGT ATAGWTFGAG AALQIPFAMQ MAYRFNGIGV TQNVLYENQK QIANQFNKAI         910        920        930        940        950        960  SQIQESLTTT STALGKLQDV VNQNAQALNT LVKQLSSNFG AISSVLNDIL SRLDKVEAEV         970        980        990       1000       1010       1020  QIDRLITGRL QSLQTYVTQQ LIRAAEIRAS ANLAATKMSE CVLGQSKRVD FCGKGYHLMS        1030       1040       1050       1060       1070       1080  FPQAAPHGVV FLHVTYVPSQ ERNFTTAPAI CHEGKAYFPR EGVFVFNGTS WFITQRNFFS        1090       1100       1110       1120       1130       1140  PQIITTDNTF VSGNCDVVIG IINNTVYDPL QPELDSFKEE LDKYFKNHTS PDVDLGDISG        1150       1160       1170       1180       1190       1200  INASVVNIQE EIDRLNEVAK NLNESLIDLQ ELGKYEQYIK RSNGLPGPIG PPGPRGRTGD        1210       1220       1230       1240       1250       1260  AGPVGPPGPP GPPGPPGPPS AGFDFSFLPQ PPQEKAHDGG RYYRANDANV VRDRDLEVDT        1270       1280       1290       1300       1310       1320  TLKSLSQQIE NIRSPEGSRK NPARTCRDLK MCHSDWKSGE YWIDPNQGCN LDAIKVFCNM        1330       1340       1350       1360       1370       1380  ETGETCVYPT QPSVAQKNWY ISKNPKDKRH VWFGESMTDG FQFEYGGQGS DPADVAIQLT        1390       1400       1410       1420       1430       1440  FLRLMSTEAS QNITYHCKNS VAYMDQQTGN LKKALLLQGS NEIEIRAEGN SRFTYSVTVD        1450       1460       1470       1480       1490  GCTSHTGAWG KTVIEYKTTK TSRLPIIDVA PLDVGAPDQE FGFDVGPVCF L

The above SARS-CoV-1 S recombinant polypeptide may comprise an N-terminal signal peptide provided in SEQ ID NO: 53.

An exemplary SARS-CoV-2 S recombinant polypeptide without a signal peptide is provided in SEQ ID NO: 1 (1509 aa):

        10         20         30         40         50         60  QCVNLTTRTQ LPPAYTNSFT RGVYYPDKVF RSSVLHSTQD LFLPFFSNVT WFHAIHVSGT          70         80         90        100        110        120  NGTKRFDNPV LPFNDGVYFA STEKSNIIRG WIFGTTLDSK TQSLLIVNNA TNVVIKVCEF         130        140        150        160        170        180  QFCNDPFLGV YYHKNNKSWM ESEFRVYSSA NNCTFEYVSQ PFLMDLEGKQ GNFKNLREFV         190        200        210        220        230        240  FKNIDGYFKI YSKHTPINLV RDLPQGFSAL EPLVDLPIGI NITRFQTLLA LHRSYLTPGD         250        260        270        280        290        300  SSSGWTAGAA AYYVGYLQPR TFLLKYNENG TITDAVDCAL DPLSETKCTL KSFTVEKGIY         310        320        330        340        350        360  QTSNFRVQPT ESIVRFPNIT NLCPFGEVFN ATRFASVYAW NRKRISNCVA DYSVLYNSAS         370        380        390        400        410        420  FSTFKCYGVS PTKLNDLCFT NVYADSFVIR GDEVRQIAPG QTGKIADYNY KLPDDFTGCV         430        440        450        460        470        480  IAWNSNNLDS KVGGNYNYLY RLFRKSNLKP FERDISTEIY QAGSTPCNGV EGFNCYFPLQ         490        500        510        520        530        540  SYGFQPTNGV GYQPYRVVVL SFELLHAPAT VCGPKKSTNL VKNKCVNFNF NGLTGTGVLT         550        560        570        580        590        600  ESNKKFLPFQ QFGRDIADTT DAVRDPQTLE ILDITPCSFG GVSVITPGTN TSNQVAVLYQ         610        620        630        640        650        660  DVNCTEVPVA IHADQLTPTW RVYSTGSNVF QTRAGCLIGA EHVNNSYECD IPIGAGICAS         670        680        690        700        710        720  YQTQTNSPRR ARSVASQSII AYTMSLGAEN SVAYSNNSIA IPTNFTISVT TEILPVSMTK         730        740        750        760        770        780  TSVDCTMYIC GDSTECSNLL LQYGSFCTQL NRALTGIAVE QDKNTQEVFA QVKQIYKTPP         790        800        810        820        830        840  IKDFGGFNFS QILPDPSKPS KRSFIEDLLF NKVTLADAGF IKQYGDCLGD IAARDLICAQ         850        860        870        880        890        900  KFNGLTVLPP LLTDEMIAQY TSALLAGTIT SGWTFGAGAA LQIPFAMQMA YRFNGIGVTQ         910        920        930        940        950        960  NVLYENQKLI ANQFNSAIGK IQDSLSSTAS ALGKLQDVVN QNAQALNTLV KQLSSNFGAI         970        980        990       1000       1010       1020  SSVLNDILSR LDKVEAEVQI DRLITGRLQS LQTYVTQQLI RAAEIRASAN LAATKMSECV        1030       1040       1050       1060       1070       1080  LGQSKRVDFC GKGYHLMSFP QSAPHGVVFL HVTYVPAQEK NFTTAPAICH DGKAHFPREG        1090       1100       1110       1120       1130       1140  VFVSNGTHWF VTQRNFYEPQ IITTDNTFVS GNCDVVIGIV NNTVYDPLQP ELDSFKEELD        1150       1160       1170       1180       1190       1200  KYFKNHTSPD VDLGDISGIN ASVVNIQKEI DRLNEVAKNL NESLIDLQEL GKYEQYIKRS        1210       1220       1230       1240       1250       1260  NGLPGPIGPP GPRGRTGDAG PVGPPGPPGP PGPPGPPSAG FDFSFLPQPP QEKAHDGGRY        1270       1280       1290       1300       1310       1320  YRANDANVVR DRDLEVDTTL KSLSQQIENI RSPEGSRKNP ARTCRDLKMC HSDWKSGEYW        1330       1340       1350       1360       1370       1380  IDPNQGCNLD AIKVFCNMET GETCVYPTQP SVAQKNWYIS KNPKDKRHVW FGESMTDGFQ        1390       1400       1410       1420       1430       1440  FEYGGQGSDP ADVAIQLTFL RLMSTEASQN ITYHCKNSVA YMDQQTGNLK KALLLQGSNE        1450       1460       1470       1480       1490       1500  IEIRAEGNSR FTYSVTVDGC TSHTGAWGKT VIEYKTTKTS RLPIIDVAPL DVGAPDQEFG       1509 FDVGPVCFL

The above SARS-CoV-2 S recombinant polypeptide may comprise an N-terminal signal peptide provided in SEQ ID NO: 54.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 1. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 1, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 1 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 2. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 2, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 2 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 3. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 3, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 3 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 4. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 4, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 4 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 5. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 5, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 5 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 6. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 6, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 6 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 7. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 7, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 7 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 8. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 8, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 8 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 9. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 9, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 9 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 10. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 10, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 10 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 11. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 11, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 11 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 12. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 12, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 12 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 13. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 13, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 13 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 14. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 14, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 14 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 15. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 15, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 15 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 16. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 16, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 16 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 17. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 17, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 17 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 18. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 18, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 18 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 19. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 19, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 19 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 20. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 20, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 20 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 21. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 21, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 21 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 22. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 22, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 22 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 23. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 23, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 23 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 24. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 24, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 24 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 25. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 25, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions, such as 13, 18, 20, 26, 69, 70, 80, 138, 142, 144, 152, 190, 215, 242, 243, 244, 246, 400, 401, 402, 417, 440, 452, 477, 484, 501, 570, 614, 655, 681, 682, 683, 684, 685, 701, 716, 888, 982, 1027, 1118, and/or 1176 (amino acid positions with respect to SEQ ID NO: 55), or any combination thereof. In some embodiments, the recombinant polypeptide is or comprises a variant of SEQ ID NO: 25 and the variant comprises any one, two, three, four, five or more of the mutations selected from the group consisting of S13I, L18F, T20N, P26S, Δ69-70 (ΔHV), D80A, D138Y, G142D, Δ144 (ΔY), W152C, R190S, D215G, Δ242-244 (ΔLAL), R246I, Δ400-402 (ΔFVI), K417T, K417N, N440K, L452R, S477N, S477G, E484K, E484Q, N501Y, A570D, D614G, H655Y, P681H, P681R, R682G, R683S, R685G, A701V, T716I, F888L, S982A, T1027I, D1118H, and V1176F, or any combination thereof.

In some embodiments, the recombinant polypeptide is or comprises the sequence set forth in SEQ ID NO: 26. In some embodiments, the recombinant polypeptide is or comprises an amino acid sequence having at least or about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 26, including a sequence comprising substitution, deletion, and/or insertion at one or more amino acid positions of SEQ ID NO: 26.

As indicated above, in some embodiments, the recombinant polypeptides provided herein associate not only to form trimers, but can also aggregate or be aggregated to generate proteins comprising a plurality of recombinant polypeptides. In some embodiments, the proteins formed have macrostructures. In some cases, the macrostructure may confer structural stability of the coronavirus viral antigen or immunogen recombinant polypeptides, which in turn can afford access to potentially antigenic sites capable of promoting an immune response.

In some embodiments, the trimerized recombinant polypeptides aggregate to form a protein containing a plurality of trimerized recombinant polypeptides. In some embodiments, the plurality of trimerized recombinant polypeptides forms a protein having a macrostructure.

In some embodiments, the proteins described herein comprising a plurality of recombinant polypeptides are an immunogen. In some embodiments, the proteins described herein comprising a plurality of recombinant polypeptides are comprised in a nanoparticle. For example, in some embodiments, the proteins are linked directly to a nanoparticle, e.g., protein nanoparticle. In some embodiments, the proteins are linked indirectly to a nanoparticle. In some embodiments, the proteins described herein comprising a plurality of recombinant polypeptides are comprised in virus-like particle (VLP).

In some embodiments, provided herein is a complex comprising a recombinant polypeptide selected from the group consisting of SEQ ID NOs: 1-26 or a fragment, variant, or mutant thereof, in any suitable combination. In some embodiments, provided herein is a complex comprising a trimer of a recombinant polypeptide selected from the group consisting of SEQ ID NOs: 1-26 or a fragment, variant, or mutant thereof, wherein the recombinant polypeptides are trimerized via inter-polypeptide disulfide bonds to form the trimer.

In some embodiments, provided herein is a fusion protein comprising a plurality of recombinant polypeptides, each recombinant polypeptide comprising, from amino to carboxy terminus: a) a first region comprising a portion of a coronavirus spike protein ectodomain that precedes a coronavirus spike protein receptor binding domain (RBD) as located in a nonchimeric coronavirus spike protein, of a first coronavirus; b) a second region comprising a coronavirus spike protein receptor binding domain (RBD) of a second coronavirus that is different from said first coronavirus; and c) a C-terminal propeptide of collagen, wherein the C-terminal propeptides of the recombinant polypeptides form inter-polypeptide disulfide bonds. In some embodiments, the fusion protein further comprises a third region between the second region and the C-terminal propeptide of collagen. In some embodiments, the third region comprises an S1 domain of a third coronavirus, wherein the third coronavirus is the same or different from the first coronavirus or second coronavirus. In some embodiments, the third region comprises an S2 domain of a fourth coronavirus, wherein the fourth coronavirus is the same or different from the first, second, or third coronavirus. In some embodiments, the first region comprises an N-terminal domain (NTD) of the first coronavirus. In some embodiments, the first region comprises one or more amino acid residues that is/are different from corresponding amino acid residue(s) in the second coronavirus. In some embodiments, the second region comprises one or more amino acid residues that is/are different from corresponding amino acid residue(s) in the first coronavirus. In some embodiments, the first and second coronaviruses are different variants or strains of the same coronavirus. In some embodiments, the first region comprises the NTD of the first coronavirus, the second region comprises the RBD of the second coronavirus, and the first and second coronaviruses are different variants of SARS-CoV-2. In some embodiments, the first coronavirus and the second coronavirus are independently selected from the group consisting of SARS-CoV-2 viruses of the B.1.526, B.1.1.143, P.2, B.1.351, P.1, B.1.1.7, B.1.617, and A.23.1 lineages.

In some embodiments, provided herein is a trimeric fusion protein comprising three recombinant polypeptides, each recombinant polypeptide comprising, from amino to carboxy terminus: a) a first region comprising a coronavirus spike protein N-terminal domain (NTD) of a SARS-CoV-2 of the B.1.526 lineage; b) a second region comprising a coronavirus spike protein receptor binding domain (RBD) of a SARS-CoV-2 of the B.1.351 lineage; and c) a C-terminal propeptide of collagen, wherein the C-terminal propeptides of the recombinant polypeptides form inter-polypeptide disulfide bonds.

In some embodiments, provided herein is a method for preventing infection by a coronavirus in a mammal, comprising immunizing a mammal with an effective amount of a fusion protein disclosed herein. In some embodiments, neutralizing antibodies against the first and the second coronaviruses are generated in the mammal. In some embodiments, the first and second coronaviruses are different variants of SARS-CoV-2, and neutralizing antibodies generated in the mammal neutralize two or more of SARS-CoV-2 viruses of the B.1.526, B.1.1.143, P.2, B.1.351, P.1, B.1.1.7, B.1.617, and A.23.1 lineages. In some embodiments, neutralizing antibodies generated in the mammal neutralize three or more of SARS-CoV-2 viruses of the B.1.526, B.1.1.143, P.2, B.1.351, P.1, B.1.1.7, B.1.617, and A.23.1 lineages. In some embodiments, the method comprises immunizing the mammal with two or more doses of the fusion protein. In some embodiments, the fusion protein is administered as a booster dose following one or more doses of an immunogen comprising a spike protein peptide comprising NTD and RBD from the same SARS-CoV-2 variant.

In some embodiments, provided herein are engineered fusion polypeptides that are derived or modified from the spike (S) glycoprotein of coronaviruses including SARS-CoV-1 and SARS-CoV-2. In some embodiments, compared to a wildtype S protein sequence of the coronavirus, the fusion polypeptides disclosed herein can be stabilized in a prefusion conformation. In some embodiments, fusion to the trimerization domain may prevent the S protein peptide in the fusion proteins from forming a straight helix (e.g., similar to what occurs during membrane fusion process). For instance, cryo-EM structures of an S-Trimer™ subunit vaccine candidate shows it predominantly adopts tightly closed pre-fusion state, unlike the full-length wild-type spike protein which forms both pre- and post-fusion states in the presence of detergent. Ma et al., J Virol (2021) doi:10.1128/JVI.00194-21. In some embodiments, the fusion proteins may comprise an altered soluble S sequence with modification(s) that inactivates the S1/S2 cleavage site; mutation(s) in the turn region between the heptad repeat 1 (HR1) region and the central helix (CH) region that prevents HR1 and CH to form a straight helix; and/or truncation of the heptad repeat 2 region (HR2) in addition to the stabilizing mutations. In some embodiments, the fusion proteins herein may but do not need to comprise one or more mutations such as K986G/V987G, K986P/V987P, K986G/V987P or K986P/V987G which are believed to stabilize the spike protein in a pre-fusion state. In some embodiments, mutations such as K986G/V987G, K986P/V987P, K986G/V987P or K986P/V987G are not necessary for stabilizing a fusion polypeptide disclosed herein comprising the Trimer-Tag™ trimerization domain.

In some of these embodiments, the mutation inactivating S1/S2 cleavage site can contain substitution of RRAR (682-685 in SEQ ID NO:55) with GSAG (SEQ ID NO: 60), and the mutation in the turn region can contain double mutation K986G/V987G, K986P/V987P, K986G/V987P or K986P/V987G. In some embodiments, truncation of HR2 entails deletion of one or more of the residues shown in SEQ ID NO: 65 at the C-terminus of the wildtype soluble S sequence. In some embodiments, the immunogen polypeptide can further include in the region of HR1 that interacts with HR2 (a) one or more proline or glycine substitutions, and/or (b) insertion of one or more amino acid residues. In some of these embodiments, the immunogen polypeptide can have one or more substitutions selected from A942P, S943P, A944P, A942G, S943G and A944G. In some of these embodiments, the insertion can be insertion of G or GS between any residues in A942-A944.

2 Polynucleotides and Vectors

Also provided are polynucleotides (nucleic acid molecules) encoding the coronavirus antigens or immunogens and recombinant polypeptides provided herein, and vectors for genetically engineering cells to express such coronavirus antigens or immunogens and recombinant polypeptides.

In some embodiments, provided are polynucleotides that encode recombinant polypeptides provided herein. In some aspects, the polynucleotide contains a single nucleic acid sequence, such as a nucleic acid sequence encoding a recombinant polypeptide. In other instances, the polynucleotide contains a first nucleic acid sequence encoding a recombinant polypeptide a particular coronavirus viral antigen or immunogen and a second nucleic acid sequence encoding a recombinant polypeptide comprising a different coronavirus viral antigen or immunogen.

In some embodiments, the polynucleotide encoding the recombinant polypeptide contains at least one promoter that is operatively linked to control expression of the recombinant polypeptide. In some embodiments, the polynucleotide contains two, three, or more promoters operatively linked to control expression of the recombinant polypeptide.

In some embodiments, for example when the polynucleotide contains two or more nucleic acid coding sequences, such as a sequences encoding recombinant polypeptides comprising different coronavirus viral antigens or immunogens, at least one promoter is operatively linked to control expression of the two or more nucleic acid sequences. In some embodiments, the polynucleotide contains two, three, or more promoters operatively linked to control expression of the recombinant polypeptides.

In some embodiments, expression of the recombinant polypeptide(s) is inducible or conditional. Thus, in some aspects, the polynucleotide encoding the recombinant polypeptide(s) contains a conditional promoter, enhancer, or transactivator. In some such aspects, the conditional promoter, enhancer, or transactivator is an inducible promoter, enhancer, or transactivator or a repressible promoter, enhancer, or transactivator. For example, in some embodiments, an inducible or conditional promoter can be used to restrict expression of the recombinant polypeptides to a specific microenvironment. In some embodiments, expression driven by the inducible or conditional promoter is regulated by exposure to an exogenous agent, such as heat, radiation, or drug.

In cases where the polynucleotide contains more than one nucleic acid sequence encoding a recombinant polypeptide, the polynucleotide may further include a nucleic acid sequence encoding a peptide between the one or more nucleic acid sequences. In some cases, the nucleic acid positioned between the nucleic acid sequences encodes a peptide that separates the translation products of the nucleic acid sequences during or after translation. In some embodiments, the peptide contains an internal ribosome entry site (IRES), a self-cleaving peptide, or a peptide that causes ribosome skipping, such as a T2A peptide.

In some embodiments, the polynucleotide encoding the recombinant polypeptide(s) is introduced into a composition containing cultured cells (e.g., host cells), such as by retroviral transduction, transfection, or transformation. In some embodiments, this can allow for expression (e.g., production) of the recombinant polypeptides. In some embodiments, the expressed recombinant polypeptides are purified.

In some embodiments, the polynucleotide (nucleic acid molecule) provided herein encodes an coronavirus viral antigen or immunogen as described herein. In some embodiments, the polynucleotide (nucleic acid molecule) provided herein encodes a recombinant polypeptide comprising coronavirus viral antigen or immunogen, e.g., coronavirus S protein peptide, as described herein.

Also provided are vectors or constructs containing nucleic acid molecules as described herein. In some embodiments, the vectors or constructs contain one or more promoters operatively linked to the nucleic acid molecule encoding the recombinant polypeptide to drive expression thereof. In some embodiments, the promoter is operatively linked to one or more than one nucleic acid molecule, e.g., nucleic acid molecule encoding recombinant polypeptides containing different coronavirus viral antigens or immunogens.

In some embodiments, the vector is a viral vector. In some embodiments the viral vector is a retroviral vector. In some embodiments, the retroviral vector is a lentiviral vector. In some embodiments, the retroviral vector is a gammaretroviral vector.

In some embodiments, the vector or construct includes a single promoter that drives the expression of one or more nucleic acid molecules of the polynucleotide. In some embodiments, such promoters can be multicistronic (bicistronic or tricistronic, see e.g., U.S. Pat. No. 6,060,273). For example, in some embodiments, transcription units can be engineered as a bicistronic unit containing an IRES (internal ribosome entry site), which allows coexpression of gene products (e.g., encoding different recombinant polypeptides) by a message from a single promoter. In some embodiments, the vectors provided herein are bicistronic, allowing the vector to contain and express two nucleic acid sequences. In some embodiments, the vectors provided herein are tricistronic, allowing the vector to contain and express three nucleic acid sequences.

In some embodiments, a single promoter directs expression of an RNA that contains, in a single open reading frame (ORF), two or three genes (e.g. encoding the chimeric signaling receptor and encoding a recombinant receptor) separated from one another by sequences encoding a self-cleavage peptide (e.g., 2A sequences) or a protease recognition site (e.g., furin). The ORF thus encodes a single polypeptide, which, either during (in the case of 2A) or after translation, is processed into the individual proteins. In some cases, the peptide, such as T2A, can cause the ribosome to skip (ribosome skipping) synthesis of a peptide bond at the C-terminus of a 2A element, leading to separation between the end of the 2A sequence and the next peptide downstream (see, for example, de Felipe. Genetic Vaccines and Ther. 2:13 (2004) and deFelipe et al. Traffic 5:616-626 (2004)). Many 2A elements are known in the art. Examples of 2A sequences that can be used in the methods and nucleic acids disclosed herein include, without limitation, 2A sequences from the foot-and-mouth disease virus (F2A), equine rhinitis A virus (E2A), Thosea asigna virus (T2A), and porcine teschovirus-1 (P2A) as described in U.S. Patent Publication No. 20070116690.

In some embodiments, the vector is comprised in a virus. In some embodiments, the virus is a pseudovirus. In some embodiments, the virus is a viral-like particle. In some embodiments, the vector is comprised in a cell. In some embodiments, the virus or cell in which the vector is comprised contains a recombinant genome.

III. Immunogenic Compositions and Formulations

In some embodiments, provided herein is an immunogenic composition comprising a trimer of a recombinant polypeptide comprising a sequence selected from the group consisting of SEQ ID NOs: 1-26, or a combination of any two or more of the trimers. In some embodiments, provided herein is an immunogenic composition comprising the trimer of the recombinant polypeptide having the sequence set forth in SEQ ID NO: 1.

In some embodiments, a unit dose of the immunogenic composition may comprise from about 10 μg to about 100 μg of the SARS-CoV-2 antigen, preferably from about 25 μg to about 75 μg of the SARS-CoV-2 antigen, preferably from about 40 μg to about 60 μg of the SARS-CoV-2 antigen, or about 50 μg of the SARS-CoV-2 antigen. In some embodiments, the dose contains 3 μg of the SARS-CoV-2 antigen. In other embodiments, the dose contains 9 μg of the SARS-CoV-2 antigen. In further embodiments, the dose contains 30 μg of the SARS-CoV-2 antigen.

In some instances it may be desirable to combine a disclosed immunogen, with other pharmaceutical products (e.g., vaccines) which induce protective responses to other agents. For example, a composition including a recombinant coronavirus S antigen as described herein, e.g., trimer or protein, can be can be administered simultaneously (typically separately) or sequentially with other vaccines recommended by the Advisory Committee on Immunization Practices (ACIP; cdc.gov/vaccines/acip/index.html) for the targeted age group (e.g., infants from approximately one to six months of age), such as an influenza vaccine or a varicella zoster vaccine. As such, a disclosed immunogen including a recombinant coronavirus S antigen described herein may be administered simultaneously or sequentially with vaccines against, for example, hepatitis B (HepB), diphtheria, tetanus and pertussis (DTaP), pneumococcal bacteria (PCV), Haemophilus influenzae type b (Hib), polio, influenza and rotavirus.

Multivalent or combination vaccines provide protection against multiple pathogens. In some aspects, multivalent vaccines can protect against multiple strains of the same pathogen. In some aspects, multivalent vaccines protect against multiple pathogens, such as the combination vaccine Tdap, which protects against strains of tentus, pertussis, and diphtheria. Multivalent vaccines are highly desirable to minimize the number of immunizations required to confer protection against multiple pathogens or pathogenic strains, to reduce administration costs, and to increase coverage rates. This can be particularly useful, for example, when vaccinating babies or children.

In some embodiments, the vaccine, e.g., comprising an immunogenic composition described herein, is a multivalent vaccine. In some embodiments, the antigenic material for incorporation into the multivalent vaccine compositions is derived from coronavirus strains or types, for examples as described herein (see, e.g., Section I). Antigens for incorporation into the multivalent vaccine compositions may be derived from one strain of coronavirus or multiple strains, for example, between two and five strains, in order to provide a broader spectrum of protection. In one embodiment, antigens for incorporation into the multivalent vaccine compositions are derived from multiple strains of coronavirus. Other useful antigens include live, attenuated and inactivated viruses such as inactivated polio virus (Jiang et al., J. Biol. Stand., (1986) 14:103-9), attenuated strains of Hepatitis A virus (Bradley et al., J. Med. Virol., (1984) 14:373-86), attenuated measles virus (James et al., N. Engl. J. Med., (1995) 332:1262-6), and epitopes of pertussis virus (for example, ACEL-IMUNE acellular DTP, Wyeth-Lederle Vaccines and Pediatrics).

In some aspects, the vaccine provided herein is a universal vaccine. In some embodiments, a universal vaccine is a vaccine which protects against multiple strains of the same virus, such as multiple strains of coronavirus. Development of an effective universal coronavirus vaccine would reduce cost and labor, e.g., with seasonal vaccine formulation, and allow for more robust pandemic preparedness.

In some aspects, a universal vaccine is one comprised of multiple epitopes derived from distinct viral strains. In some aspects, a universal vaccine is comprised of a single epitope that is conserved across distinct viral strains. For example, a universal vaccine can be based on the relatively conserved domain(s) of the S protein.

Immunogenic compositions comprising a disclosed immunogen (e.g., a disclosed recombinant coronavirus S antigen or nucleic acid molecule encoding a protomer of disclosed recombinant coronavirus S antigen) and a pharmaceutically acceptable carrier are also provided. In some embodiments, the immunogenic composition comprises trimerized recombinant polypeptides provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a protein comprising a plurality of trimerized recombinant polypeptides provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition a protein nanoparticle provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a VLP as provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises an isolated nucleic acid provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a vector as provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a virus as provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a pseudovirus provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition comprises a cell as provided herein, and optionally a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition, such as described herein, is a vaccine. In some embodiments, the vaccine is a prophylactic vaccine. In some embodiments, the vaccine is a therapeutic vaccine. In some embodiments, the vaccine is a prophylactic vaccine and a therapeutic vaccine. Such pharmaceutical compositions can be administered to subjects by a variety of administration modes known to the person of ordinary skill in the art, for example, intramuscular, intradermal, subcutaneous, intravenous, intra-arterial, intra-articular, intraperitoneal, intranasal, sublingual, tonsillar, oropharyngeal, or other parenteral and mucosal routes. In several embodiments, pharmaceutical compositions including one or more of the disclosed immunogens are immunogenic compositions. Actual methods for preparing administrable compositions will be known or apparent to those skilled in the art and are described in more detail in such publications as Remingtons Pharmaceutical Sciences, 19th Ed., Mack Publishing Company, Easton, Pa., 1995.

Thus, an immunogen, e.g., recombinant coronavirus S antigen, e.g., trimer, protein, described herein can be formulated with pharmaceutically acceptable carriers to help retain biological activity while also promoting increased stability during storage within an acceptable temperature range. Potential carriers include, but are not limited to, physiologically balanced culture medium, phosphate buffer saline solution, water, emulsions (e.g., oil/water or water/oil emulsions), various types of wetting agents, cryoprotective additives or stabilizers such as proteins, peptides or hydrolysates (e.g., albumin, gelatin), sugars (e.g., sucrose, lactose, sorbitol), amino acids (e.g., sodium glutamate), or other protective agents. The resulting aqueous solutions may be packaged for use as is or lyophilized. Lyophilized preparations are combined with a sterile solution prior to administration for either single or multiple dosing.

Formulated compositions, especially liquid formulations, may contain a bacteriostat to prevent or minimize degradation during storage, including but not limited to effective concentrations (usually 1% w/v) of benzyl alcohol, phenol, m-cresol, chlorobutanol, methylparaben, and/or propylparaben. A bacteriostat may be contraindicated for some patients; therefore, a lyophilized formulation may be reconstituted in a solution either containing or not containing such a component.

The immunogenic compositions of the disclosure can contain as pharmaceutically acceptable vehicles substances as required to approximate physiological conditions, such as pH adjusting and buffering agents, tonicity adjusting agents, wetting agents and the like, for example, sodium acetate, sodium lactate, sodium chloride, potassium chloride, calcium chloride, sorbitan monolaurate, and triethanolamine oleate. The immunogenic composition may optionally include an adjuvant to enhance an immune response of the host. Suitable adjuvants are, for example, toll-like receptor (TLR) agonists, alum, AlPO₄, alhydrogel, Lipid-A and derivatives or variants thereof, oil-emulsions, saponins, neutral liposomes, liposomes containing the vaccine and cytokines, non-ionic block copolymers, and chemokines. Non-ionic block polymers containing polyoxyethylene (POE) and polyxylpropylene (POP), such as POE-POP-POE block copolymers, MPL™ (3-O-deacylated monophosphoryl lipid A; Corixa, Hamilton, Ind.) and IL-12 (Genetics Institute, Cambridge, Mass.), among many other suitable adjuvants well known in the art, may be used as an adjuvant (Newman et al., 1998, Critical Reviews in Therapeutic Drug Carrier Systems 15:89-142). These adjuvants have the advantage in that they help to stimulate the immune system in a non-specific way, thus enhancing the immune response to a pharmaceutical product. In some embodiments, the immunogenic compositions of the disclosure may include or be administered with more than one adjuvant. In some embodiments, the immunogenic compositions of the disclosure may include or be administered with two adjuvants. In some embodiments, the immunogenic compositions of the disclosure may include or be administered with a plurality of adjuvants. For example, in some cases, a vaccine, e.g., comprising an immunogenic composition provided herein, may include or be administered in combination with a plurality of adjuvants.

For vaccine compositions, examples of suitable adjuvants include, e.g., aluminum hydroxide, lecithin, Freund's adjuvant, MPL™ and IL-12. In some embodiments, the vaccine compositions or nanoparticle immunogens disclosed herein (e.g., SARS-COV-2 vaccine composition) can be formulated as a controlled-release or time-release formulation. This can be achieved in a composition that contains a slow release polymer or via a microencapsulated delivery system or bioadhesive gel. The various pharmaceutical compositions can be prepared in accordance with standard procedures well known in the art.

In some embodiments, the immunogenic compositions of the disclosure can contain an adjuvant formulation comprising a metabolizable oil (e.g., squalene) and alpha tocopherol in the form of an oil-in-water emulsion, and polyoxyethylene sorbitan monooleate (Tween-80). In some embodiments, the adjuvant formulation can comprise from about 2% to about 10% squalene, from about 2 to about 10% alpha tocopherol (e.g., D-alpha-tocopherol) and from about 0.3 to about 3% polyoxyethylene sorbitan monooleate. In some embodiments, the adjuvant formulation can comprise about 5% squalene, about 5% tocopherol, and about 0.4% polyoxyethylene sorbitan monooleate. In some embodiments, the immunogenic compositions of the disclosure can contain 3 de-O-acylated monophosphoryl lipid A (3D-MPL), and an adjuvant in the form of an oil in water emulsion, which adjuvant contains a metabolizable oil, alpha tocopherol, and polyoxyethylene sorbitan monoleate. In some embodiments, the immunogenic compositions of the disclosure can contain QS21 (extract of Quillaja saponaria Molina: fraction 21), 3D-MPL and an oil in water emulsion wherein the oil in water emulsion comprises a metabolizable oil, alpha tocopherol and polyoxyethelene sorbitan monooleate. In some embodiments, the immunogenic compositions of the disclosure can contain QS21, 3D-MPL and an oil in water emulsion wherein the oil in water emulsion has the following composition: a metabolisible oil, such as squalene, alpha tocopherol and Tween-80. In some embodiments, the immunogenic compositions of the disclosure can contain an adjuvant in the form of a liposome composition.

In some embodiments, the immunogenic compositions of the disclosure can contain an adjuvant formulation comprising a metabolizable oil (e.g., squalene), polyoxyethylene sorbitan monooleate (Tween-80), and Span 85. In some embodiments, the adjuvant formulation can comprise about 5% (w/v) squalene, about 0.5% (w/v) polyoxyethylene sorbitan monooleate, and about 0.5% (w/v) Span 85.

In some embodiments, the immunogenic compositions of the disclosure can contain an adjuvant formulation comprising Quillaja saponins, cholesterol, and phosphorlipid, e.g., in the form of a nanoparticle composition. In some embodiments, the immunogenic compositions of the disclosure can contain a mixture of separately purified fractions of Quillaja saponaria Molina where are subsequently formulated with cholesterol and phospholipid.

In some embodiments, the immunogenic compositions of the disclosure can contain an adjuvant selected from the group consisting of MF59™, Matrix-A™, Matrix-C™, Matrix-M™, AS01, AS02, AS03, and AS04.

In some embodiments, the immunogenic compositions of the disclosure can contain a toll-like receptor 9 (TLR9) agonist, wherein the TLR9 agonist is an oligonucleotide of from 8 to 35 nucleotides in length comprising an unmethylated cytidine-phospho-guanosine (also referred to as CpG or cytosine-phosphate-guanosine) motif, and the SARS-CoV-2 antigen and the oligonucleotide are present in the immunogenic composition in amounts effective to stimulate an immune response against the SARS-CoV-2 antigen in a mammalian subject, such as a human subject in need thereof. TLR9 (CD289) recognizes unmethylated cytidine-phospho-guanosine (CpG) motifs found in microbial DNA, which can be mimicked using synthetic CpG-containing oligodeoxynucleotides (CpG-ODNs). CpG-ODNs are known to enhance antibody production and to stimulate T helper 1 (Th1) cell responses (Coffman et al., Immunity, 33:492-503, 2010). Optimal oligonucleotide TLR9 agonists often contain a palindromic sequence following the general formula of: 5′-purine-purine-CG-pyrimidine-pyrimidine-3′, or 5′-purine-purine-CG-pyrimidine-pyrimidine-CG-3′. U.S. Pat. No. 6,589,940, which is incorporated herein by reference in its entirety. In some embodiments, the CpG oligonucleotide is linear. In other embodiments, the CpG oligonucleotide is circular or includes hairpin loop(s). The CpG oligonucleotide may be single stranded or double stranded. In some embodiments, the CpG oligonucleotide may contain modifications. Modifications include but are not limited to, modifications of the 3′OH or 5′OH group, modifications of the nucleotide base, modifications of the sugar component, and modifications of the phosphate group. Modified bases may be included in the palindromic sequence of the CpG oligonucleotide as long as the modified base(s) maintains the same specificity for its natural complement through Watson-Crick base pairing (e.g., the palindromic portion is still self-complementary). In some embodiments, the CpG oligonucleotide comprises a non-canonical base. In some embodiments, the CpG oligonucleotide comprises a modified nucleoside. In some embodiments, the modified nucleoside is selected from the group consisting of 2′-deoxy-7-deazaguanosine, 2′-deoxy-6-thioguanosine, arabinoguanosine, 2′-deoxy-2′substituted-arabinoguanosine, and 2′-O-substituted-arabinoguanosine. The CpG oligonucleotide may contain a modification of the phosphate group. For example, in addition to phosphodiester linkages, phosphate modifications include, but are not limited to, methyl phosphonate, phosphorothioate, phosphoramidate (bridging or non-bridging), phosphotriester and phosphorodithioate and may be used in any combination. Other non-phosphate linkages may also be used. In some embodiments, the oligonucleotides comprise only phosphorothioate backbones. In some embodiments, the oligonucleotides comprise only phosphodiester backbones. In some embodiments, the oligonucleotide comprises a combination of phosphate linkages in the phosphate backbone such as a combination of phosphodiester and phosphorothioate linkages. Oligonucleotides with phosphorothioate backbones can be more immunogenic than those with phosphodiester backbones and appear to be more resistant to degradation after injection into the host (Braun et al., J Immunol, 141:2084-2089, 1988; and Latimer et al., Mol Immunol, 32:1057-1064, 1995). The CpG oligonucleotides of the present disclosure include at least one, two or three internucleotide phosphorothioate ester linkages. In some embodiments, when a plurality of CpG oligonucleotide molecules are present in a pharmaceutical composition comprising at least one excipient, both stereoisomers of the phosphorothioate ester linkage are present in the plurality of CpG oligonucleotide molecules. In some embodiments, all of the internucleotide linkages of the CpG oligonucleotide are phosphorothioate linkages, or said another way, the CpG oligonucleotide has a phosphorothioate backbone.

Any suitable CpG oligodeoxynucleotides (ODNs) or combinations thereof can be used as adjuvants in the present disclosure. For instance, K-type ODNs (also referred to as B type) encode multiple CpG motifs on a phosphorothioate backbone. K-type ODNs may be based on the following sequence TCCATGGACGTTCCTGAGCGTT. The use of phosphorothioate nucleotides enhances resistance to nuclease digestion when compared with native phosphodiester nucleotides, resulting in a substantially longer in vivo half life. K-type ODNs trigger pDCs to differentiate and produce TNF-α, and B cells to proliferate and secrete IgM. D-type ODNs (also referred to as A type) are constructed of a mixed phosphodiester/phosphorothioate backbone, contain a single CpG motif flanked by palindromic sequences and have poly G tails at the 3′ and 5′ ends (a structural motif that facilitates the formation of concatamers). D-type ODNs may be based on the following sequence GGTGCATCGATGCAGGGGGG. D-type ODNs trigger pDCs to mature and secrete IFN-α, but have no effect on B cells. C-type ODNs resemble K-type in being composed entirely of phosphorothioate nucleotides, but resemble D-type in containing palindromic CpG motifs. C-type ODNs may be based on the following sequence TCGTCGTTCGAACGACGTTGAT. This class of ODNs stimulate B cells to secrete IL-6 and pDCs to produce IFN-α. P-type ODNs contain two palindromic sequences, enabling them to form higher ordered structures. P-type ODNs may be based on the following sequence TCGTCGACGATCGGCGCGCGCCG. P-type ODNs activate B cells and pDCs, and induce substantially greater IFN-α production when compared with C-type ODNs. In this paragraph, bold letters in ODN sequences indicate self-complementary palindromes and CpG motifs are underlined.

Exemplary CpG ODNs, e.g., CpG 7909 (5′-TCGTCGTTTTGTCGTTTTGTCGTT-3′) and CpG 1018 (5′-TGACTGTGAACGTTCGAGATGA-3′), are known and disclosed in U.S. Pat. Nos. 7,255,868, 7,491,706, 7,479,285, 7,745,598, 7,785,610, 8,003,115, 8,133,874, 8,114,418, 8,222,398, 8,333,980, 8,597,665, 8,669,237, 9,028,845, and 10,052,378; application publication US 2020/0002704; and Bode et al., “CpG DNA as a vaccine adjuvant”, Expert Rev Vaccines (2011), 10(4): 499-511, all of which are incorporated herein by reference in their entireties for all purposes.

One or more adjuvants may be used in combination and may include, but are not limited to, alum (aluminum salts), oil-in-water emulsions, water-in-oil emulsions, liposomes, and microparticles, such as poly(lactide-co-glycolide) microparticles (Shah et al., Methods Mol Biol, 1494:1-14, 2017). In some embodiments, the immunogenic compositions further comprises an aluminum salt adjuvant to which the SARS-CoV-2 antigen is adsorbed. In some embodiments, the aluminum salt adjuvant comprises one or more of the group consisting of amorphous aluminum hydroxyphosphate sulfate, aluminum hydroxide, aluminum phosphate, and potassium aluminum sulfate. In some embodiments, the aluminum salt adjuvant comprises one or both of aluminum hydroxide and aluminum phosphate. In some embodiments, the aluminum salt adjuvant comprises aluminum hydroxide. In some embodiments, a unit dose of the immunogenic composition comprises from about 0.25 to about 0.50 mg Al³⁺, or about 0.35 mg Al³⁺. In some embodiments, the immunogenic composition further comprises an additional adjuvant. Other suitable adjuvants include, but are not limited to, squalene-in-water emulsion (e.g., MF59 or AS03), TLR3 agonists (e.g., poly-IC or poly-ICLC), TLR4 agonists (e.g., bacterial lipopolysaccharide derivatives such monophosphoryl lipid A (MPL), and/or a saponin such as Quil A or QS-21, as in AS01 or AS02), a TLR5 agonist (bacterial flagellin), and TLR7, TLR8 and/or TLR9 agonists (imidazoquinoline derivatives such as imiquimod, and resiquimod) (Coffman et al., Immunity, 33:492-503, 2010). In some embodiments, the additional adjuvant comprises MPL and alum (e.g., AS04). For veterinary use and for production of antibodies in non-human animals, mitogenic components of Freund's adjuvant (both complete and incomplete) can be used.

In some embodiments, the immunogenic compositions comprise pharmaceutically acceptable excipients including for instance, solvents, bulking agents, buffering agents, tonicity adjusting agents, and preservatives (Pramanick et al., Pharma Times, 45:65-77, 2013). In some embodiments the immunogenic compositions may comprise an excipient that functions as one or more of a solvent, a bulking agent, a buffering agent, and a tonicity adjusting agent (e.g., sodium chloride in saline may serve as both an aqueous vehicle and a tonicity adjusting agent).

In some embodiments, the immunogenic compositions comprise an aqueous vehicle as a solvent. Suitable vehicles include for instance sterile water, saline solution, phosphate buffered saline, and Ringer's solution. In some embodiments, the composition is isotonic.

The immunogenic compositions may comprise a buffering agent. Buffering agents control pH to inhibit degradation of the active agent during processing, storage and optionally reconstitution. Suitable buffers include for instance salts comprising acetate, citrate, phosphate or sulfate. Other suitable buffers include for instance amino acids such as arginine, glycine, histidine, and lysine. The buffering agent may further comprise hydrochloric acid or sodium hydroxide. In some embodiments, the buffering agent maintains the pH of the composition within a range of 6 to 9. In some embodiments, the pH is greater than (lower limit) 6, 7 or 8. In some embodiments, the pH is less than (upper limit) 9, 8, or 7. That is, the pH is in the range of from about 6 to 9 in which the lower limit is less than the upper limit.

The immunogenic compositions may comprise a tonicity adjusting agent. Suitable tonicity adjusting agents include for instance dextrose, glycerol, sodium chloride, glycerin and mannitol.

The immunogenic compositions may comprise a bulking agent. Bulking agents are particularly useful when the pharmaceutical composition is to be lyophilized before administration. In some embodiments, the bulking agent is a protectant that aids in the stabilization and prevention of degradation of the active agents during freeze or spray drying and/or during storage. Suitable bulking agents are sugars (mono-, di- and polysaccharides) such as sucrose, lactose, trehalose, mannitol, sorbital, glucose and raffinose.

The immunogenic compositions may comprise a preservative. Suitable preservatives include for instance antioxidants and antimicrobial agents. However, in preferred embodiments, the immunogenic composition is prepared under sterile conditions and is in a single use container, and thus does not necessitate inclusion of a preservative.

In some embodiments, the composition can be provided as a sterile composition. The pharmaceutical composition typically contains an effective amount of a disclosed immunogen and can be prepared by conventional techniques. Typically, the amount of immunogen in each dose of the immunogenic composition is selected as an amount which induces an immune response without significant, adverse side effects. In some embodiments, the composition can be provided in unit dosage form for use to induce an immune response in a subject. A unit dosage form contains a suitable single preselected dosage for administration to a subject, or suitable marked or measured multiples of two or more preselected unit dosages, and/or a metering mechanism for administering the unit dose or multiples thereof. In other embodiments, the composition further includes an adjuvant.

IV. Methods of Inducing an Immune Response

In some embodiments, provided herein is a method for generating an immune response to a surface antigen of a coronavirus in a subject, comprising administering to the subject an effective amount of a complex comprising a recombinant polypeptide selected from the group consisting of SEQ ID NOs: 1-26. In some embodiments, provided herein is a method for generating an immune response to a surface antigen of a coronavirus in a subject, wherein the surface antigen comprises an S protein or antigenic fragment thereof, and the method comprises administering to the subject an effective amount of a complex comprising a recombinant polypeptide selected from the group consisting of SEQ ID NOs: 1-26. In some embodiments, provided herein is a method for generating an immune response to a surface antigen of a coronavirus in a subject, wherein the surface antigen comprises a sequence selected from the group consisting of SEQ ID NOs: 27-66, and the method comprises administering to the subject an effective amount of a complex comprising a recombinant polypeptide selected from the group consisting of SEQ ID NOs: 1-26. In some embodiments, provided herein is a method for generating an immune response to a surface antigen of a coronavirus in a subject, wherein the surface antigen comprises an S protein or antigenic fragment thereof of the coronavirus and optionally the surface antigen comprises the sequence set forth in SEQ ID NO: 55 or antigenic fragment thereof, and the method comprises administering to the subject an effective amount of a complex comprising a recombinant polypeptide comprising the sequence set forth in any one of SEQ ID NOs: 10-25.

In some embodiments, provided herein is a method for generating an immune response to a surface antigen of a coronavirus in a subject, wherein the surface antigen comprises an S protein or antigenic fragment thereof, and the method comprises administering to the subject an effective amount of a complex comprising a recombinant polypeptide comprising the sequence selected from the group consisting of SEQ ID NOs: 1-26, or a combination of any two or more of the complexes. In some embodiments, the method comprises administering to the subject an effective amount of the complex comprising the recombinant polypeptide comprising the sequence set forth in SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, and/or SEQ ID NO: 13.

The disclosed immunogens (e.g., recombinant coronavirus S antigen, e.g., an S-Trimer™ or an S protein described herein, a nucleic acid molecule (such as an RNA molecule) or vector encoding a protomer of a disclosed recombinant coronavirus S antigen, or a protein nanoparticle or virus like particle comprising a disclosed recombinant coronavirus S antigen) can be administered to a subject to induce an immune response to the corresponding coronavirus S antigen in the subject. In a particular example, the subject is a human. The immune response can be a protective immune response, for example a response that inhibits subsequent infection with the corresponding coronavirus. Elicitation of the immune response can also be used to treat or inhibit infection and illnesses associated with the corresponding coronavirus.

A subject can be selected for treatment that has, or is at risk for developing infection with the coronavirus, for example because of exposure or the possibility of exposure to the coronavirus. Following administration of a disclosed immunogen, the subject can be monitored for infection or symptoms associated with coronavirus, or both.

Typical subjects intended for treatment with the therapeutics and methods of the present disclosure include humans, as well as non-human primates and other animals. To identify subjects for prophylaxis or treatment according to the methods of the disclosure, accepted screening methods are employed to determine risk factors associated with a targeted or suspected disease or condition, or to determine the status of an existing disease or condition in a subject. These screening methods include, for example, conventional work-ups to determine environmental, familial, occupational, and other such risk factors that may be associated with the targeted or suspected disease or condition, as well as diagnostic methods, such as various ELISA and other immunoassay methods to detect and/or characterize coronavirus infection. These and other routine methods allow the clinician to select patients in need of therapy using the methods and pharmaceutical compositions of the disclosure. In accordance with these methods and principles, a composition can be administered according to the teachings herein, or other conventional methods, as an independent prophylaxis or treatment program, or as a follow-up, adjunct or coordinate treatment regimen to other treatments.

The administration of a disclosed immunogen, e.g., coronavirus S antigen, e.g., trimer, protein, can be for prophylactic or therapeutic purpose. When provided prophylactically, the disclosed therapeutic agents are provided in advance of any symptom, for example, in advance of infection. The prophylactic administration of the disclosed therapeutic agents serves to prevent or ameliorate any subsequent infection. When provided therapeutically, the disclosed therapeutic agents are provided at or after the onset of a symptom of disease or infection, for example, after development of a symptom of infection with coronavirus corresponding to the coronavirus S antigen, or after diagnosis with the coronavirus infection. The therapeutic agents can thus be provided prior to the anticipated exposure to coronavirus so as to attenuate the anticipated severity, duration or extent of an infection and/or associated disease symptoms, after exposure or suspected exposure to the virus, or after the actual initiation of an infection.

The immunogens described herein, and immunogenic compositions thereof, are provided to a subject in an amount effective to induce or enhance an immune response against the coronavirus S antigen in the subject, preferably a human. The actual dosage of disclosed immunogen will vary according to factors such as the disease indication and particular status of the subject (for example, the subject's age, size, fitness, extent of symptoms, susceptibility factors, and the like), time and route of administration, other drugs or treatments being administered concurrently, as well as the specific pharmacology of the composition for eliciting the desired activity or biological response in the subject. Dosage regimens can be adjusted to provide an optimum prophylactic or therapeutic response.

An immunogenic composition including one or more of the disclosed immunogens can be used in coordinate (or prime-boost) vaccination protocols or combinatorial formulations. In certain embodiments, novel combinatorial immunogenic compositions and coordinate immunization protocols employ separate immunogens or formulations, each directed toward eliciting an anti-viral immune response, such as an immune response to coronavirus S antigen. Separate immunogenic compositions that elicit the anti-viral immune response can be combined in a polyvalent immunogenic composition administered to a subject in a single immunization step, or they can be administered separately (in monovalent immunogenic compositions) in a coordinate (or prime-boost) immunization protocol.

There can be several boosts, and each boost can be a different disclosed immunogen. In some examples that the boost may be the same immunogen as another boost, or the prime. The prime and boost can be administered as a single dose or multiple doses, for example two doses, three doses, four doses, five doses, six doses or more can be administered to a subject over days, weeks or months. Multiple boosts can also be given, such one to five (e.g., 1, 2, 3, 4 or 5 boosts), or more. Different dosages can be used in a series of sequential immunizations. For example a relatively large dose in a primary immunization and then a boost with relatively smaller doses.

In some embodiments, the boost can be administered about two, about three to eight, or about four, weeks following the prime, or about several months after the prime. In some embodiments, the boost can be administered about 5, about 6, about 7, about 8, about 10, about 12, about 18, about 24, months after the prime, or more or less time after the prime. Periodic additional boosts can also be used at appropriate time points to enhance the subject's “immune memory.” The adequacy of the vaccination parameters chosen, e.g., formulation, dose, regimen and the like, can be determined by taking aliquots of serum from the subject and assaying antibody titers during the course of the immunization program. In addition, the clinical condition of the subject can be monitored for the desired effect, e.g., prevention of infection or improvement in disease state (e.g., reduction in viral load). If such monitoring indicates that vaccination is sub-optimal, the subject can be boosted with an additional dose of immunogenic composition, and the vaccination parameters can be modified in a fashion expected to potentiate the immune response.

In some embodiments, the prime-boost method can include DNA-primer and protein-boost vaccination protocol to a subject. The method can include two or more administrations of the nucleic acid molecule or the protein.

For protein therapeutics, typically, each human dose will comprise 1-1000 μg of protein, such as from about 1 μg to about 100 μg, for example, from about 1 μg to about 50 μg, such as about 1 μg, about 2 μg, about 5 μg, about 10 μg, about 15 μg, about 20 μg, about 25 μg, about 30 μg, about 40 μg, or about 50 μg.

The amount utilized in an immunogenic composition is selected based on the subject population (e.g., infant or elderly). An optimal amount for a particular composition can be ascertained by standard studies involving observation of antibody titers and other responses in subjects. It is understood that a therapeutically effective amount of a disclosed immunogen, such as a disclosed recombinant coronavirus S antigen, e.g., trimer, protein, viral vector, or nucleic acid molecule in a immunogenic composition, can include an amount that is ineffective at eliciting an immune response by administration of a single dose, but that is effective upon administration of multiple dosages, for example in a prime-boost administration protocol.

Upon administration of a disclosed immunogen of this disclosure, the immune system of the subject typically responds to the immunogenic composition by producing antibodies specific for the coronavirus S protein peptide included in the immunogen. Such a response signifies that an immunologically effective dose was delivered to the subject.

In some embodiments, the antibody response of a subject will be determined in the context of evaluating effective dosages/immunization protocols. In most instances it will be sufficient to assess the antibody titer in serum or plasma obtained from the subject. Decisions as to whether to administer booster inoculations and/or to change the amount of the therapeutic agent administered to the individual can be at least partially based on the antibody titer level. The antibody titer level can be based on, for example, an immunobinding assay which measures the concentration of antibodies in the serum which bind to an antigen including, for example, the recombinant coronavirus S antigen, e.g., an S-Trimer™

The coronavirus infection does not need to be completely eliminated or reduced or prevented for the methods to be effective. For example, elicitation of an immune response to a coronavirus with one or more of the disclosed immunogens can reduce or inhibit infection with the coronavirus by a desired amount, for example, by at least 10%, at least 20%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or even at least 100% (elimination or prevention of detectable infected cells), as compared to infection with the coronavirus in the absence of the immunogen. In additional examples, coronavirus replication can be reduced or inhibited by the disclosed methods. Coronavirus replication does not need to be completely eliminated for the method to be effective. For example, the immune response elicited using one or more of the disclosed immunogens can reduce replication of the corresponding coronavirus by a desired amount, for example, by at least 10%, at least 20%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or even at least 100% (elimination or prevention of detectable replication of the coronavirus), as compared to replication of the coronavirus in the absence of the immune response.

In some embodiments, the disclosed immunogen is administered to the subject simultaneously with the administration of the adjuvant. In other embodiments, the disclosed immunogen is administered to the subject after the administration of the adjuvant and within a sufficient amount of time to induce the immune response.

One approach to administration of nucleic acids is direct immunization with plasmid DNA, such as with a mammalian expression plasmid. Immunization by nucleic acid constructs is well known in the art and taught, for example, in U.S. Pat. No. 5,643,578 (which describes methods of immunizing vertebrates by introducing DNA encoding a desired antigen to elicit a cell-mediated or a humoral response), and U.S. Pat. Nos. 5,593,972 and 5,817,637 (which describe operably linking a nucleic acid sequence encoding an antigen to regulatory sequences enabling expression). U.S. Pat. No. 5,880,103 describes several methods of delivery of nucleic acids encoding immunogenic peptides or other antigens to an organism. The methods include liposomal delivery of the nucleic acids (or of the synthetic peptides themselves), and immune-stimulating constructs, or ISCOMS™, negatively charged cage-like structures of 30-40 nm in size formed spontaneously on mixing cholesterol and Quil A™ (saponin). Protective immunity has been generated in a variety of experimental models of infection, including toxoplasmosis and Epstein-Barr virus-induced tumors, using ISCOMS™ as the delivery vehicle for antigens (Mowat and Donachie, Immunol. Today 12:383, 1991). Doses of antigen as low as 1 μg encapsulated in ISCOMS™ have been found to produce Class I mediated CTL responses (Takahashi et al., Nature 344:873, 1990).

In some embodiments, a plasmid DNA vaccine is used to express a disclosed immunogen in a subject. For example, a nucleic acid molecule encoding a disclosed immunogen can be administered to a subject to induce an immune response to the coronavirus S antigen. In some embodiments, the nucleic acid molecule can be included on a plasmid vector for DNA immunization, such as the pVRC8400 vector (described in Barouch et al., J. Virol, 79, 8828-8834, 2005, which is incorporated by reference herein).

In another approach to using nucleic acids for immunization, a disclosed recombinant coronavirus S antigen, e.g., trimer, protein, can be expressed by attenuated viral hosts or vectors or bacterial vectors. Recombinant vaccinia virus, adeno-associated virus (AAV), herpes virus, retrovirus, cytogmeglo virus or other viral vectors can be used to express the peptide or protein, thereby eliciting a CTL response. For example, vaccinia vectors and methods useful in immunization protocols are described in U.S. Pat. No. 4,722,848. BCG (Bacillus Calmette Guerin) provides another vector for expression of the peptides (see Stover, Nature 351:456-460, 1991).

In one embodiment, a nucleic acid encoding a disclosed recombinant coronavirus S antigen is introduced directly into cells. For example, the nucleic acid can be loaded onto gold microspheres by standard methods and introduced into the skin by a device such as Bio-Rad's HELIOS™ Gene Gun. The nucleic acids can be “naked,” consisting of plasmids under control of a strong promoter. Typically, the DNA is injected into muscle, although it can also be injected directly into other sites. Dosages for injection are usually around 0.5 μg/kg to about 50 mg/kg, and typically are about 0.005 mg/kg to about 5 mg/kg (see, e.g., U.S. Pat. No. 5,589,466).

For example, the nucleic acid can be loaded onto gold microspheres by standard methods and introduced into the skin by a device such as Bio-Rad's HELIOS™ Gene Gun. The nucleic acids can be “naked,” consisting of plasmids under control of a strong promoter. Typically, the DNA is injected into muscle, although it can also be injected directly into other sites. Dosages for injection are usually around 0.5 μg/kg to about 50 mg/kg, and typically are about 0.005 mg/kg to about 5 mg/kg (see, e.g., U.S. Pat. No. 5,589,466).

In another embodiment, an mRNA-based immunization protocol can be used to deliver a nucleic acid encoding a disclosed recombinant coronavirus S antigen directly into cells. In some embodiments, nucleic acid-based vaccines based on mRNA may provide a potent alternative to the previously mentioned approaches. mRNA vaccines preclude safety concerns about DNA integration into the host genome and can be directly translated in the host cell cytoplasm. Moreover, the simple cell-free, in vitro synthesis of RNA avoids the manufacturing complications associated with viral vectors. Two exemplary forms of RNA-based vaccination that can be used to deliver a nucleic acid encoding a disclosed recombinant coronavirus S antigen include conventional non-amplifying mRNA immunization (see, e.g., Petsch et al., “Protective efficacy of in vitro synthesized, specific mRNA vaccines against influenza A virus infection,” Nature biotechnology, 30(12):1210-6, 2012) and self-amplifying mRNA immunization (see, e.g., Geall et al., “Nonviral delivery of self-amplifying RNA vaccines,” PNAS, 109(36): 14604-14609, 2012; Magini et al., “Self-Amplifying mRNA Vaccines Expressing Multiple Conserved Influenza Antigens Confer Protection against Homologous and Heterosubtypic Viral Challenge,” PLoS One, 11(8):e0161193, 2016; and Brito et al., “Self-amplifying mRNA vaccines,” Adv Genet., 89:179-233, 2015).

In some embodiments, administration of a therapeutically effective amount of one or more of the disclosed immunogens to a subject induces a neutralizing immune response in the subject. To assess neutralization activity, following immunization of a subject, serum can be collected from the subject at appropriate time points, frozen, and stored for neutralization testing. Methods to assay for neutralization activity are known to the person of ordinary skill in the art and are further described herein, and include, but are not limited to, plaque reduction neutralization (PRNT) assays, microneutralization assays, flow cytometry based assays, single-cycle infection assays. In some embodiments, the serum neutralization activity can be assayed using a panel of coronavirus pseudoviruses.

In some embodiments, administration of a therapeutically effective amount of one or more of the disclosed immunogens to a subject induces a neutralizing immune response in the subject. To assess neutralization activity, following immunization of a subject, serum can be collected from the subject at appropriate time points, frozen, and stored for neutralization testing. Methods to assay for neutralization activity are known to the person of ordinary skill in the art and are further described herein, and include, but are not limited to, plaque reduction neutralization (PRNT) assays, microneutralization assays, flow cytometry based assays, single-cycle infection assays. In some embodiments, the serum neutralization activity can be assayed using a panel of coronavirus pseudoviruses.

In some embodiments, a neutralizing immune response induced by the disclosed immunogens herein generates a neutralizing antibody against a coronavirus such as SARS-CoV-2. In some embodiments, the neutralizing antibody herein binds to a cellular receptor or coreceptor of a coronavirus such as SARS-CoV-2 or component thereof. In some embodiments, the viral receptor or coreceptor is a coronavirus receptor or coreceptor, preferably a pneumonia virus receptor or coreceptor, more preferably a human coronavirus receptor such as SARS-CoV-2 receptor or coreceptor. In some embodiments, the neutralizing antibody herein modulates, decreases, antagonizes, mitigates, blocks, inhibits, abrogates and/or interferes with at least one coronavirus such as SARS-CoV-2 activity or binding, or with a coronavirus such as SARS-CoV-2 receptor activity or binding, in vitro, in situ and/or in vivo, such as SARS-CoV-2 release, SARS-CoV-2 receptor signaling, membrane SARS-CoV-2 cleavage, SARS-CoV-2 activity, SARS-CoV-2 production and/or synthesis. In some embodiments, the disclosed immunogens herein induce neutralizing antibodies against SARS-CoV-2 that modulate, decrease, antagonize, mitigate, block, inhibit, abrogate and/or interfere with SARS-CoV-2 binding to a SARS-CoV-2 receptor or coreceptor, such as angiotensin converting enzyme 2 (ACE2), dipeptidyl peptidase 4 (DPP4), dendritic cell-specific intercellular adhesion molecule-3-grabbing non integrin (DC-SIGN), and/or liver/lymph node-SIGN (L-SIGN).

V. Articles of Manufacture or Kits

Also provided are articles of manufacture or kits containing the provided recombinant polypeptide, proteins, and immunogenic compositions. The articles of manufacture may include a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, test tubes, IV solution bags, etc. The containers may be formed from a variety of materials such as glass or plastic. In some embodiments, the container has a sterile access port. Exemplary containers include an intravenous solution bags, vials, including those with stoppers pierceable by a needle for injection. The article of manufacture or kit may further include a package insert indicating that the compositions can be used to treat a particular condition such as a condition described herein (e.g., coronavirus infection). Alternatively, or additionally, the article of manufacture or kit may further include another or the same container comprising a pharmaceutically-acceptable buffer. It may further include other materials such as other buffers, diluents, filters, needles, and/or syringes.

The label or package insert may indicate that the composition is used for treating an coronavirus infection in an individual. The label or a package insert, which is on or associated with the container, may indicate directions for reconstitution and/or use of the formulation. The label or package insert may further indicate that the formulation is useful or intended for subcutaneous, intravenous, or other modes of administration for treating or preventing a coronavirus infection in an individual.

The container in some embodiments holds a composition which is by itself or combined with another composition effective for treating, preventing and/or diagnosing the condition. The article of manufacture or kit may include (a) a first container with a composition contained therein (i.e., first medicament), wherein the composition includes the immunogenic composition or protein or recombinant polypeptide thereof; and (b) a second container with a composition contained therein (i.e., second medicament), wherein the composition includes a further agent, such as an adjuvant or otherwise therapeutic agent, and which article or kit further comprises instructions on the label or package insert for treating the subject with the second medicament, in an effective amount.

Terminology

Unless defined otherwise, all terms of art, notations and other technical and scientific terms or terminology used herein are intended to have the same meaning as is commonly understood by one of ordinary skill in the art to which the claimed subject matter pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art.

The terms “polypeptide” and “protein” are used interchangeably to refer to a polymer of amino acid residues, and are not limited to a minimum length. Polypeptides, including the provided receptors and other polypeptides, e.g., linkers or peptides, may include amino acid residues including natural and/or non-natural amino acid residues. The terms also include post-expression modifications of the polypeptide, for example, glycosylation, sialylation, acetylation, and phosphorylation. In some aspects, the polypeptides may contain modifications with respect to a native or natural sequence, as long as the protein maintains the desired activity. These modifications may be deliberate, as through site-directed mutagenesis, or may be accidental, such as through mutations of hosts which produce the proteins or errors due to PCR amplification.

As used herein, a “subject” is a mammal, such as a human or other animal, and typically is human. In some embodiments, the subject, e.g., patient, to whom the agent or agents, cells, cell populations, or compositions are administered, is a mammal, typically a primate, such as a human. In some embodiments, the primate is a monkey or an ape. The subject can be male or female and can be any suitable age, including infant, juvenile, adolescent, adult, and geriatric subjects. In some embodiments, the subject is a non-primate mammal, such as a rodent.

As used herein, “treatment” (and grammatical variations thereof such as “treat” or “treating”) refers to complete or partial amelioration or reduction of a disease or condition or disorder, or a symptom, adverse effect or outcome, or phenotype associated therewith. Desirable effects of treatment include, but are not limited to, preventing occurrence or recurrence of disease, alleviation of symptoms, diminishment of any direct or indirect pathological consequences of the disease, preventing metastasis, decreasing the rate of disease progression, amelioration or palliation of the disease state, and remission or improved prognosis. The terms do not imply complete curing of a disease or complete elimination of any symptom or effect(s) on all symptoms or outcomes.

As used herein, “delaying development of a disease” means to defer, hinder, slow, retard, stabilize, suppress and/or postpone development of the disease (such as cancer). This delay can be of varying lengths of time, depending on the history of the disease and/or individual being treated. In some embodiments, sufficient or significant delay can, in effect, encompass prevention, in that the individual does not develop the disease. For example, a late stage cancer, such as development of metastasis, may be delayed.

“Preventing,” as used herein, includes providing prophylaxis with respect to the occurrence or recurrence of a disease in a subject that may be predisposed to the disease but has not yet been diagnosed with the disease. In some embodiments, the provided cells and compositions are used to delay development of a disease or to slow the progression of a disease.

As used herein, to “suppress” a function or activity is to reduce the function or activity when compared to otherwise same conditions except for a condition or parameter of interest, or alternatively, as compared to another condition. For example, cells that suppress tumor growth reduce the rate of growth of the tumor compared to the rate of growth of the tumor in the absence of the cells.

An “effective amount” of an agent, e.g., a pharmaceutical formulation, cells, or composition, in the context of administration, refers to an amount effective, at dosages/amounts and for periods of time necessary, to achieve a desired result, such as a therapeutic or prophylactic result.

A “therapeutically effective amount” of an agent, e.g., a pharmaceutical formulation or cells, refers to an amount effective, at dosages and for periods of time necessary, to achieve a desired therapeutic result, such as for treatment of a disease, condition, or disorder, and/or pharmacokinetic or pharmacodynamic effect of the treatment. The therapeutically effective amount may vary according to factors such as the disease state, age, sex, and weight of the subject, and the populations of cells administered. In some embodiments, the provided methods involve administering the cells and/or compositions at effective amounts, e.g., therapeutically effective amounts.

A “prophylactically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result. Typically but not necessarily, since a prophylactic dose is used in subjects prior to or at an earlier stage of disease, the prophylactically effective amount will be less than the therapeutically effective amount. In the context of lower tumor burden, the prophylactically effective amount in some aspects will be higher than the therapeutically effective amount. Effective amount of a vaccine or other agent that is sufficient to generate a desired response, such as reduce or eliminate a sign or symptom of a condition or disease, such as pneumonia. For instance, this can be the amount necessary to inhibit viral replication or to measurably alter outward symptoms of the viral infection. In general, this amount will be sufficient to measurably inhibit virus (for example, SARS-CoV-2) replication or infectivity. When administered to a subject, a dosage will generally be used that will achieve target tissue concentrations that has been shown to achieve in vitro inhibition of viral replication. In some embodiments, an “effective amount” is one that treats (including prophylaxis) one or more symptoms and/or underlying causes of any of a disorder or disease, for example to treat a coronavirus infection. In some embodiments, an effective amount is a therapeutically effective amount. In some embodiments, an effective amount is an amount that prevents one or more signs or symptoms of a particular disease or condition from developing, such as one or more signs or symptoms associated with coronaviral infections.

As used herein, the terms “antigen” or “immunogen” are used interchangeably to refer to a substance, typically a protein, which is capable of inducing an immune response in a subject. The term also refers to proteins that are immunologically active in the sense that once administered to a subject (either directly or by administering to the subject a nucleotide sequence or vector that encodes the protein) is able to evoke an immune response of the humoral and/or cellular type directed against that protein. Unless otherwise noted, the term “vaccine immunogen” is used interchangeably with “protein antigen” or “immunogen polypeptide”.

The term “conservatively modified variant” applies to both amino acid and nucleic acid sequences. With respect to particular nucleic acid sequences, conservatively modified variants refer to those nucleic acids which encode identical or essentially identical amino acid sequences, or where the nucleic acid does not encode an amino acid sequence, to essentially identical sequences. Because of the degeneracy of the genetic code, a large number of functionally identical nucleic acids encode any given protein. For polypeptide sequences, “conservatively modified variants” refer to a variant which has conservative amino acid substitutions, amino acid residues replaced with other amino acid residue having a side chain with a similar charge. Families of amino acid residues having side chains with similar charges have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

Epitope refers to an antigenic determinant. These are particular chemical groups or peptide sequences on a molecule that are antigenic, such that they elicit a specific immune response, for example, an epitope is the region of an antigen to which B and/or T cells respond. Epitopes can be formed both from contiguous amino acids or noncontiguous amino acids juxtaposed by tertiary folding of a protein.

Unless otherwise noted, a fusion protein is a recombinant protein containing amino acid sequence from at least two unrelated proteins that have been joined together, via a peptide bond, to make a single protein. Thus, it does not encompass the naturally existing coronaviruses surface antigen that is termed fusion (F) protein as described herein. The unrelated amino acid sequences can be joined directly to each other or they can be joined using a linker sequence. As used herein, proteins are unrelated, if their amino acid sequences are not normally found joined together via a peptide bond in their natural environment (e.g., inside a cell). For example, the amino acid sequences of a viral antigen and the amino acid sequences of a collagen or procollagen are not normally found joined together via a peptide bond.

Immunogen is a protein or a portion thereof that is capable of inducing an immune response in a mammal, such as a mammal infected or at risk of infection with a pathogen. Administration of an immunogen can lead to protective immunity and/or proactive immunity against a pathogen of interest.

Immunogenic composition refers to a composition comprising an immunogenic polypeptide that induces a measurable CTL response against virus expressing the immunogenic polypeptide, or induces a measurable B cell response (such as production of antibodies) against the immunogenic polypeptide.

Sequence identity or similarity between two or more nucleic acid sequences, or two or more amino acid sequences, is expressed in terms of the identity or similarity between the sequences. Sequence identity can be measured in terms of percentage identity; the higher the percentage, the more identical the sequences are. Two sequences are “substantially identical” if two sequences have a specified percentage of amino acid residues or nucleotides that are the same (i.e., 60% identity, optionally 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% identity over a specified region, or, when not specified, over the entire sequence), when compared and aligned for maximum correspondence over a comparison window, or designated region as measured using one of the following sequence comparison algorithms or by manual alignment and visual inspection. Optionally, the identity exists over a region that is at least about 50 nucleotides (or 10 amino acids) in length, or more preferably over a region that is 100 to 500 or 1000 or more nucleotides (or 20, 50, 200 or more amino acids) in length.

Vaccine refers to a pharmaceutical composition that elicits a prophylactic or therapeutic immune response in a subject. In some cases, the immune response is a protective immune response. Typically, a vaccine elicits an antigen-specific immune response to an antigen of a pathogen, for example a viral pathogen, or to a cellular constituent correlated with a pathological condition. A vaccine may include a polynucleotide (such as a nucleic acid encoding a disclosed antigen), a peptide or polypeptide (such as a disclosed antigen), a virus, a cell or one or more cellular constituents. In some embodiments, vaccines or vaccine immunogens or vaccine compositions are expressed from fusion constructs and self-assemble into nanoparticles displaying an immunogen polypeptide or protein on the surface.

Virus-like particle (VLP) refers to a non-replicating, viral shell, derived from any of several viruses. VLPs are generally composed of one or more viral proteins, such as, but not limited to, those proteins referred to as capsid, coat, shell, surface and/or envelope proteins, or particle-forming polypeptides derived from these proteins. VLPs can form spontaneously upon recombinant expression of the protein in an appropriate expression system. Methods for producing particular VLPs are known in the art. The presence of VLPs following recombinant expression of viral proteins can be detected using conventional techniques known in the art, such as by electron microscopy, biophysical characterization, and the like. See, for example, Baker et al. (1991) Biophys. J. 60:1445-1456; and Hagensee et al. (1994) J. Virol. 68:4503-4505. For example, VLPs can be isolated by density gradient centrifugation and/or identified by characteristic density banding. Alternatively, cryoelectron microscopy can be performed on vitrified aqueous samples of the VLP preparation in question, and images recorded under appropriate exposure conditions.

The term “about” as used herein refers to the usual error range for the respective value readily known to the skilled person in this technical field. Reference to “about” a value or parameter herein includes (and describes) embodiments that are directed to that value or parameter per se.

As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. For example, “a” or “an” means “at least one” or “one or more.”

Throughout this disclosure, various aspects of the claimed subject matter are presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the claimed subject matter. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, where a range of values is provided, it is understood that each intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the claimed subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the claimed subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the claimed subject matter. This applies regardless of the breadth of the range.

As used herein, a composition refers to any mixture of two or more products, substances, or compounds, including cells. It may be a solution, a suspension, liquid, powder, a paste, aqueous, non-aqueous or any combination thereof.

The term “vector,” as used herein, refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes the vector as a self-replicating nucleic acid structure as well as the vector incorporated into the genome of a host cell into which it has been introduced. Certain vectors are capable of directing the expression of nucleic acids to which they are operatively linked. Such vectors are referred to herein as “expression vectors.”

Exemplary Embodiments

Embodiment 1. A protein comprising a plurality of recombinant polypeptides, each recombinant polypeptide comprising a surface antigen of a coronavirus linked to a C-terminal propeptide of collagen, wherein the C-terminal propeptides of the recombinant polypeptides form inter-polypeptide disulfide bonds.

Embodiment 2. The protein of embodiment 1, wherein the coronavirus is a Severe Acute Respiratory Syndrome (SARS)-coronavirus (SARS-CoV), a SARS-coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, a Middle East Respiratory Syndrome (MERS)-coronavirus (MERS-CoV), a MERS-like coronavirus, NL63-CoV, 229E-CoV, OC43-CoV, HKU1-CoV, WIV1-CoV, MHV, HKU9-CoV, PEDV-CoV, or SDCV.

Embodiment 3. The protein of embodiment 1 or 2, wherein the surface antigen comprises a coronavirus spike (S) protein or a fragment or epitope thereof, wherein the epitope is optionally a linear epitope or a conformational epitope, and wherein the protein comprises three recombinant polypeptides.

Embodiment 4. The protein of embodiment 3, wherein the surface antigen comprises a signal peptide, an S1 subunit peptide, an S2 subunit peptide, or any combination thereof.

Embodiment 5. The protein of embodiment 3, wherein the surface antigen comprises a signal peptide, a receptor binding domain (RBD) peptide, a receptor binding motif (RBM) peptide, a fusion peptide (FP), a heptad repeat 1 (HR1) peptide, or a heptad repeat 2 (HR2) peptide, or any combination thereof.

Embodiment 6. The protein of any of embodiments 3-5, wherein the surface antigen comprises a receptor binding domain (RBD) of the S protein.

Embodiment 7. The protein of any of embodiments 3-6, wherein the surface antigen comprises an S1 subunit and an S2 subunit of the S protein.

Embodiment 8. The protein of any of embodiments 3-7, wherein the surface antigen does not comprise a transmembrane (TM) domain peptide and/or a cytoplasm (CP) domain peptide.

Embodiment 9. The protein of any of embodiments 3-8, wherein the surface antigen comprises a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, thrombin, or cathepsin L.

Embodiment 10. The protein of any of embodiments 3-8, wherein the surface antigen does not comprise a protease cleavage site, wherein the protease is optionally furin, trypsin, factor Xa, thrombin, or cathepsin L.

Embodiment 11. The protein of any of embodiments 1-10, wherein the surface antigen is soluble or does not directly bind to a lipid bilayer, e.g., a membrane or viral envelope.

Embodiment 12. The protein of any of embodiments 1-11, wherein the surface antigens are the same or different among the recombinant polypeptides of the protein.

Embodiment 13. The protein of any of embodiments 1-12, wherein the surface antigen is directly fused to the C-terminal propeptide, or is linked to the C-terminal propeptide via a linker, such as a linker comprising glycine-X-Y repeats, wherein X and Y and independently any amino acid and optionally proline or hydroxyproline.

Embodiment 14. The protein of any of embodiments 1-13, which is soluble or does not directly bind to a lipid bilayer, e.g., a membrane or viral envelope.

Embodiment 15. The protein of any of embodiments 1-14, wherein the protein is capable of binding to a cell surface receptor of a subject, optionally wherein the subject is a mammal such as a primate, e.g., human.

Embodiment 16. The protein of embodiment 15, wherein the cell surface receptor is angiotensin converting enzyme 2 (ACE2), dipeptidyl peptidase 4 (DPP4), dendritic cell-specific intercellular adhesion molecule-3-grabbing non integrin (DC-SIGN), or liver/lymph node-SIGN (L-SIGN).

Embodiment 17. The protein of any of embodiments 1-16, wherein the C-terminal propeptide is of human collagen.

Embodiment 18. The protein of any of embodiments 1-17, wherein the C-terminal propeptide comprises a C-terminal polypeptide of proα1(I), proα1(II), proα1(III), proα1(V), proα1(XI), proα2(I), proα2(V), proα2(XI), or proα3(XI), or a fragment thereof.

Embodiment 19. The protein of any of embodiments 1-18, wherein the C-terminal propeptides are the same or different among the recombinant polypeptides.

Embodiment 20. The protein of any of embodiments 1-19, wherein the C-terminal propeptide comprises any of SEQ ID NOs: 67-80 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 21. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 67 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 22. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 68 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 23. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 69 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 24. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 70 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 25. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 71 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 26. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 72 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 27. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 73 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 28. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 74 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 29. The protein of any of embodiments 1-20, wherein the C-terminal propeptide comprises SEQ ID NO: 75 or SEQ ID NO: 76 or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 30. The protein of any of embodiments 1-29, wherein the C-terminal propeptide comprises a sequence comprising glycine-X-Y repeats linked to the N-terminus of any of SEQ ID NOs: 67-80, wherein X and Y and independently any amino acid and optionally proline or hydroxyproline, or an amino acid sequence at least 90% identical thereto capable of forming inter-polypeptide disulfide bonds and trimerizing the recombinant polypeptides.

Embodiment 31. The protein of any of embodiments 1-30, wherein the surface antigen in each recombinant polypeptide is in a prefusion conformation or a postfusion conformation.

Embodiment 32. The protein of any of embodiments 1-31, wherein the surface antigen in each recombinant polypeptide comprises any of SEQ ID NOs: 27-66 or an amino acid sequence at least 80% identical thereto.

Embodiment 33. The protein of any of embodiments 1-32, wherein the recombinant polypeptide comprises any of SEQ ID NOs: 1-26 or an amino acid sequence at least 80% identical thereto.

Embodiment 34. An immunogen comprising the protein of any of embodiments 1-33.

Embodiment 35. A protein nanoparticle comprising the protein of any of embodiments 1-33 directly or indirectly linked to a nanoparticle.

Embodiment 36. A virus-like particle (VLP) comprising the protein of any of embodiments 1-33.

Embodiment 37. An isolated nucleic acid encoding one, two, three or more of the recombinant polypeptides of the protein of any of embodiments 1-33.

Embodiment 38. The isolated nucleic acid of embodiment 37, wherein a polynucleotide encoding the surface antigen is fused in-frame to a polynucleotide encoding the C-terminal propeptide of collagen.

Embodiment 39. The isolated nucleic acid of embodiment 37 or 38, which is operably linked to a promoter.

Embodiment 40. The isolated nucleic acid of any of embodiments 37-39, which is a DNA molecule.

Embodiment 41. The isolated nucleic acid of any of embodiments 37-39, which is an RNA molecule, optionally an mRNA molecule such as a nucleoside-modified mRNA, a non-amplifying mRNA, a self-amplifying mRNA, or a trans-amplifying mRNA.

Embodiment 42. A vector comprising the isolated nucleic acid of any of embodiments 37-41.

Embodiment 43. The vector of embodiment 42, which is a viral vector.

Embodiment 44. A virus, a pseudovirus, or a cell comprising the vector of embodiment 42 or 43, optionally wherein the virus or cell has a recombinant genome.

Embodiment 45. An immunogenic composition comprising the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, or cell of any one of embodiments 1-44, and a pharmaceutically acceptable carrier.

Embodiment 46. A vaccine comprising the immunogenic composition of embodiment 45 and optionally an adjuvant, wherein the vaccine is optionally a subunit vaccine, and/or optionally wherein the vaccines is a prophylactic and/or therapeutic vaccine.

Embodiment 47. The vaccine of embodiment 46, wherein the vaccine comprises a plurality of different adjuvants.

Embodiment 48. A method of producing a protein, comprising: expressing the isolated nucleic acid or vector of any one of embodiments 37-43 in a host cell to produce the protein of any of embodiments 1-33; and purifying the protein.

Embodiment 49. The protein produced by the method of embodiment 48.

Embodiment 50. A method for generating an immune response to a surface antigen of a coronavirus in a subject, comprising administering to the subject an effective amount of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine of any one of embodiments 1-47 and 49 to generate the immune response.

Embodiment 51. The method of embodiment 50, for treating or preventing infection with the coronavirus.

Embodiment 52. The method of embodiment 50 or 51, wherein generating the immune response inhibits or reduces replication of the coronavirus in the subject.

Embodiment 53. The method of any of embodiments 50-52, wherein the immune response comprises a cell-mediated response and/or a humoral response, optionally comprising production of one or more neutralizing antibody, such as a polyclonal antibody or a monoclonal antibody.

Embodiment 54. The method of any of embodiments 50-53, wherein the immune response is against the surface antigen of the coronavirus but not against the C-terminal propeptide.

Embodiment 55. The method of any of embodiments 50-54, wherein the administering does not lead to antibody dependent enhancement (ADE) in the subject due to prior exposure to one or more coronavirus.

Embodiment 56. The method of any of embodiments 50-55, wherein the administering does not lead to antibody dependent enhancement (ADE) in the subject when subsequently exposed to one or more coronavirus.

Embodiment 57. The method of any of embodiments 50-56, further comprising a priming step and/or a boosting step.

Embodiment 58. The method of any of embodiments 50-57, wherein the administering step is performed via topical, transdermal, subcutaneous, intradermal, oral, intranasal (e.g., intranasal spray), intratracheal, sublingual, buccal, rectal, vaginal, inhaled, intravenous (e.g., intravenous injection), intraarterial, intramuscular (e.g., intramuscular injection), intracardiac, intraosseous, intraperitoneal, transmucosal, intravitreal, subretinal, intraarticular, peri-articular, local, or epicutaneous administration.

Embodiment 59. The method of any of embodiments 50-58, wherein the effective amount is administered in a single dose or a series of doses separated by one or more interval.

Embodiment 60. The method of any of embodiments 50-59, wherein the effective amount is administered without an adjuvant.

Embodiment 61. The method of any of embodiments 50-59, wherein the effective amount is administered with an adjuvant or a plurality of adjuvants.

Embodiment 62. A method comprising administering to a subject an effective amount of the protein of any one of embodiments 1-33 to generate in the subject a neutralizing antibody or neutralizing antisera to the coronavirus.

Embodiment 63. The method of embodiment 62, wherein the subject is a mammal, optionally a human or a non-human primate.

Embodiment 64. The method of embodiment 62 or 63, further comprising isolating the neutralizing antibody or neutralizing antisera from the subject.

Embodiment 65. The method of embodiment 64, further comprising administering an effective amount of the isolated neutralizing antibody or neutralizing antisera to a human subject via passive immunization to prevent or treat an infection by the coronavirus.

Embodiment 66. The method of any of embodiments 62-65, wherein the neutralizing antibody or neutralizing antisera comprises polyclonal antibodies to the coronavirus surface antigen, optionally wherein the neutralizing antibody or neutralizing antisera is free or substantially free of antibodies to the C-terminal propeptide of collagen.

Embodiment 67. The method of any of embodiments 62-65, wherein the neutralizing antibody comprises a monoclonal antibody to the coronavirus surface antigen, optionally wherein the neutralizing antibody is free or substantially free of antibodies to the C-terminal propeptide of collagen.

Embodiment 68. The protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine of any one of embodiments 1-47 and 49, for use in inducing an immune response to a coronavirus in a subject, and/or in treating or preventing an infection by the coronavirus.

Embodiment 69. Use of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine of any one of embodiments 1-47 and 49, for inducing an immune response to a coronavirus in a subject, and/or for treating or preventing an infection by the coronavirus.

Embodiment 70. Use of the protein, immunogen, protein nanoparticle, VLP, isolated nucleic acid, vector, virus, pseudovirus, cell, immunogenic composition, or vaccine of any one of embodiments 1-47 and 49, for the manufacture of a medicament or a prophylactic for inducing an immune response to a coronavirus in a subject, and/or for treating or preventing an infection by the coronavirus.

Embodiment 71. A method for analyzing a sample, comprising: contacting a sample with the protein of any of embodiments 1-33, and detecting a binding between the protein and an analyte capable of specific binding to the surface antigen of the coronavirus.

Embodiment 72. The method of embodiment 71, wherein the analyte is an antibody, a receptor, or a cell recognizing the surface antigen.

Embodiment 73. The method of embodiment 71 or 72, wherein the binding indicates the presence of the analyte in the sample, and/or an infection by the coronavirus in a subject from which the sample is derived.

Embodiment 74. A kit comprising the protein of any of embodiments 1-33 and a substrate, pad, or vial containing or immobilizing the protein, optionally wherein the kit is an ELISA or lateral flow assay kit.

EXAMPLES

The following examples are included for illustrative purposes only and are not intended to limit the scope of the present disclosure.

Example 1: Generation of Recombinant Disulfide-Bond Linked SARS-CoV-2 S-Trimer™ Fusion Protein as a Subunit Vaccine

Secreted forms of recombinant disulfide bond-linked polypeptides comprising SARS-CoV-2 protein peptides fused to a trimerization domain as candidate protein subunit vaccines were generated. In one example, the complete ecto-domain of the native spike protein (S) from SARS-CoV2, including its signal peptide (SP), S1 and S2 domains, was fused in-frame at the C-terminus to a mammalian expression vector that encoded human C-propeptide of al collagen, to enable expression of a secreted and trimeric S-Trimer™ fusion antigen, e.g., as shown in FIG. 1.

High-level expression of S-Trimer™ fusion protein was shown in FIG. 2. An 8% SDS-PAGE analysis of S-Trimer™ expression from a fed-batch serum-free CHO cell culture in a 10 L bioreactor. 10 μL of cell-free conditioned medium from Day 6 to Day 11 were analyzed under reducing condition followed by Coomassie Blue staining. A highly purified S-Trimer™ was loaded on the gel as a reference standard (Std). The full-length S-Trimer™ and partially cleaved forms at S1/S2 furin site were as indicated.

Covalently linked S-Trimer™ molecules were then purified and characterized. S-Trimer™ was purified from the cleared cell cultured medium via a Protein A (PA) affinity chromatography and anion exchange column (Q) followed by ultra-filtration and diafiltration (UF/DF) to obtain the drug substance (DS), as shown in FIG. 3A. Four μg of purified protein was analyzed against starting cell culture medium feed by an 8% reducing SDS-PAGE and stained with Coomassie Blue. The S-Trimer™ was partially cleaved at the S1/S2 furin cleavage site, but the cleaved S1 subunit appeared to be bound to the S-Trimer™ since it was co-purified with the S-Trimer™. As shown in FIG. 3B, the S-Trimer™ is a disulfide bond-linked trimer. Four μg of highly purified native-like S-Trimer™ was analyzed by a 6% SDS-PAGEs under non-reducing and reducing conditions as indicated and stained with Coomassie Blue. The S-Trimer™ was purified to nearly homogeneity as judged by SEC-HPLC analysis, with some cleaved S1 being separated during the size exclusion chromatography, as shown in FIG. 3C. The molecular weight of S-Trimer™was estimated to be 660 Kda. In FIG. 3D, the receptor binding kinetics of S-Trimer™ to ACE2-Fc was assessed by Fortebio biolayer interferometry measurements using a protein A sensor.

The S-Trimer™ molecules were highly glycosylated with N-linked glycans. Highly purified S-Trimer™ before and after digestion with either endoglycanase F (PNGase F) alone or PNGase F plus endo-O-glycosidase to remove N- and O-linked glycans, and analyzed by an 8% reducing SDS-PAGE and stained with Coomassie Blue. The full-length S-Trimer™, S2-Trimer™ and cleaved S1 before and after deglycosylation were as indicated in FIG. 4. Highly purified S-Trimer™ molecules were visualized by negative EM using FEI Tecnai spirit electron microscopy, with the predicted conformation of S-Trimer™ shown in FIG. 5.

Example 2: Functional Characterization of Recombinant Polypeptides Comprising S-Trimer™ Protein Peptides

Sera from multiple patients who had recently recovered from COVID-19 were analyzed with S-Trimer™ as an antigen to determine S-specific antibody titers (FIG. 6, Left Panel) and neutralizing antibody levels via inhibition of S-Trimer™ binding to ACE2 receptor (FIG. 6, Right Panel). The results show that S-specific antibodies and neutralizing antibodies were successfully detected from convalescent sera using S-Trimer™ as an antigen.

To further evaluate the immunogenicity and protective efficacy of exemplary recombinant polypeptides generated as described in Example 1, FIG. 7A and FIG. 7B show the induction of antigen-specific antibodies and neutralizing antibodies, respectively, in rats with S-Trimer™ alone (30 micrograms) and without any adjuvant. Similar to data shown in human in FIG. 6, these results show that antigen-specific antibodies as well as neutralizing antibodies were induced with the S-Trimer™ vaccine. Similarly, immunogenicity of the S-Trimer™ was shown in mice. Balb-c mice grouped in 6 were immunized twice at Day 1 and Day 14 with either 3 micrograms of S-Trimer™ alone or S-Trimer™+Alum (aluminum hydroxide) as an adjuvant. The antisera collected at Day 28 were analyzed with S-Trimer™ to determine the antibody titers (FIG. 7C). S-Trimer™ adjuvanted with a squalene-based adjuvant exhibited strong ability to induce antigen-specific antibodies as well as neutralizing antibodies, as shown in FIG. 7D and FIG. 7E, respectively. GMT stands for geometric mean titer.

Example 3: Broad Neutralization of Viruses Induced by an S-Trimer™ Vaccine Composition

Beginning in late 2020, the emergence and spread of multiple variant SARS-CoV-2 strains harboring mutations which may enable immune escape necessitates the rapid evaluation of second generation vaccines, with the goal of inducing optimized immune responses that are broadly protective. This example demonstrates in a mouse immunogenicity study that two doses of a modified B.1.351 spike (S)-Trimer™ vaccine candidate (B.1.351 S-Trimer™) can induce strong humoral immune responses that can broadly neutralize the original strain (Wuhan-Hu-1), UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1) strains of SARS-CoV-2. Furthermore, while immunization with two doses (prime-boost) of a prototype S-Trimer™ vaccine (based on the original SARS-CoV-2 strain) induced lower levels of cross-reactive neutralization against the B.1.351 variant, a third dose (booster dose) administered with either the prototype S-Trimer™ or B.1.351 S-Trimer™ was able to increase neutralizing antibody titers against B.1.351 to levels comparable to neutralizing antibody titers against the original strain elicited by two doses of the prototype S-Trimer™

Despite the tremendous progress and unprecedented speed of development of COVID-19 vaccines, a new record for daily COVID-19 cases was set in April 2021, over 16 months after the SARS-CoV-2 virus outbreak first emerged. Total deaths caused by COVID-19 surpassed 3 million in May 2021, with 1 million deaths having accumulated in the prior 3 months alone.

Most concerning is the emergence of multiple new SARS-CoV-2 variants of concern (VOC) starting in late 2020 that is concurrent with a surge in COVID-19 cases globally. These VOCs appear to be associated with mutations in the spike (S) protein which could potentially increase the rate of viral transmission and/or escape immunity induced by vaccination with first-wave COVID-19 vaccines based on the original strain of SARS-CoV-2 (Wuhan-Hu-1). The emergence and spread of the B.1.1.7 variant in the United Kingdom (UK), B.1.351 variant in South Africa and P.1 variant in Brazil have led to their classification as VOCs. These VOCs all include the N501Y mutation in the receptor-binding domain (RBD) of the S protein that is reported to increase transmission by 40% to 70%. The B.1.351 and P.1 variants have two additional RBD mutations—E484K and K417—that may allow immune escape from antibodies induced by prototype vaccines and natural infection.

Randomized, controlled clinical trials of prototype COVID-19 vaccines suggest decreased vaccine efficacy against VOCs compared to original SARS-CoV-2 strains. NVX-CoV2373, an adjuvanted protein-based COVID-19 vaccine, demonstrated 89% efficacy in the UK (where B.1.1.7 predominates) but only 49% efficacy in South Africa (where B.1.351 predominates). ChAdOx1, an adenovirus-vectored COVID-19 vaccine, demonstrated only 10% efficacy against the B.1.351 variant. Pfizer vaccines demonstrated 75% effectiveness against the B.1.351 variant whereas 95% efficacy was demonstrated against the original strain. Subjects vaccinated with Coronavac, an inactivated SARS-CoV-2 vaccine based on the original SARS-CoV-2 strain, demonstrated no detectable neutralizing antibody titers against P.1.

While there is some encouraging evidence that the prototype COVID-19 vaccines are likely to protect against severe disease and death caused by the VOCs, lower vaccine efficacy against any COVID-19 disease with increased transmission rates could make achieving herd immunity particularly difficult, a problem that could be further compounded by the shortage of COVID-19 vaccines globally. If not effectively controlled, the rapid global spread of SARS-CoV-2 VOCs could potentially lead to the continued emergence of new variants of interest or VOCs potentially harboring new escape mutations, such as the Indian variant (B.1.617) which emerged concurrent with a massive spike in COVID-19 cases in the spring of 2021 and has now been declared a new VOC by the WHO.

These circumstances necessitate the rapid evaluation of booster dose strategies in order to enhance neutralizing antibody responses to VOCs and the development of second generation COVID-19 vaccines which may confer optimized broadly-protective, cross-neutralizing characteristics. In this study, a modified B.1.351 Spike-Trimer™ antigen (dubbed “B.1.351 S-Trimer™”) was generated and compared with a prototype S-Trimer™ (Liang et al., Nat. Comms., 12:1346, 2021; Richmond et al., Lancet, 397: 682-694, 2021) in a mouse immunogenicity study. Heterologous prime-boost and bivalent vaccine approaches were also evaluated, as well as the effect of a third dose (booster dose).

Results Detection of Cross-Reactive Neutralizing Antibodies in Human COVID-19 Convalescent Sera

Eight human convalescent serum (HCS) samples with moderate-to-high antibody titers collected from COVID-19 patients infected with the original strain were analyzed for SARS-CoV-2 pseudovirus neutralization titers (FIG. 9A) and ACE2-competitive ELISA titers (FIG. 9B) against the original strain, UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1) strains. Neutralizing antibody titers in HCS against B.1.1.7 appeared to be similar to the original strain, and differences in ACE2-competitive titers were also not statistically significant. However, significantly lower antibody titers in HCS were observed against B.1.351 (7- to 9-fold lower) and P.1 (2- to 3-fold lower) compared to titers against the original strain.

Production and Characterization of Spike Antigens Based on Original and B.1.351 Strains

Covalently-trimerized S-protein antigens were produced based on the original SARS-CoV-2 strain (Prototype S-Trimer™) and South African variant (B.1.351 S-Trimer™) utilizing Trimer-Tag™ technology (Liang et al., Nat. Comms., 12:1346, 2021). Prototype S-Trimer™ is based on the native spike ectodomain sequences of the original SARS-CoV-2 strain (Wuhan-Hu-1), whereas the modified B.1.351 S-Trimer™ (SEQ ID NO: 10) contains 3 RBD mutations (K417N, E484K, N501Y) and the D614G mutations found in the B.1.351 variant strain, while the N-terminal domain (NTD) and S2 sequences are based on the original strain (FIG. 10A).

The binding affinity (K_(D)) of purified S-Trimer™ antigens to the human ACE2 receptor using ForteBio BioLayer interferometry was shown to be approximately 5.2 nM for Prototype S-Trimer™ and 1.5 nM for B.1.351 S-Trimer™ (FIG. 10B). The 3- to 4-fold higher ACE2 binding affinity of the B.1.351 S-Trimer™ compared to Prototype S-Trimer™ is similar to previously-reported results.

Immunogenicity of Prototype and B.1.351 S-Trimer™ Prime-Boost (2 Dose) Regimens in Mice

BALB/c mice were immunized in Stage 1 of the study (FIGS. 10C-10D) with either two doses (Day 0 and Day 21) of Prototype S-Trimer™, heterologous prime-boost (Dose 1 Prototype S-Trimer™+Dose 2 B.1.351 S-Trimer™), two doses of B.1.351 S-Trimer™, or two doses of bivalent vaccine (Prototype S-Trimer™ mixed with B.1.351 S-Trimer™). All animals in Stage 1 received an adjuvanted priming dose (Dose 1) comprising Alum (aluminum hydroxide). For the second dose (boost), half of the animals in each group received an adjuvanted boost comprising Alum (aluminum hydroxide), and the other half received non-adjuvanted boost (antigen-only). Humoral immunogenicity analysis was conducted on Day 35 blood samples (2 weeks post-dose 2) based on pseudovirus neutralization titers against the original strain and three VOCs (B.1.1.7, B.1.351 and P.1).

Neutralizing antibody titers against B.1.351 and P.1 were highest in the groups receiving two doses of either B.1.351 S-Trimer™ and bivalent vaccine (FIG. 11A), with the former inducing the numerically-highest titers. Compared to animals receiving two doses of Prototype S-Trimer™ animals receiving two doses of B.1.351 S-Trimer™ observed 13.8-fold higher neutralizing antibody titers against B.1.351 pseudovirus and 2.4-fold higher titers against P.1 pseudovirus. Interestingly, the group receiving heterologous prime boost (Dose 1 Prototype S-Trimer™+Dose 2 B.1.351 S-Trimer™) did not induce higher antibody titers against B.1.351 and P.1 compared to animals receiving two doses of Prototype S-Trimer™

Neutralizing antibody titers against the original and B.1.1.7 variant pseudoviruses were similar across all vaccine groups (FIG. 11A), demonstrating that two doses of the B.1.351 vaccine were able to elicit antibodies which are capable of fully back-neutralizing against the original strain and can also fully protect against the B.1.1.7 variant.

ACE2-competitive ELISA results were consistent with and further confirmed the pseudovirus neutralization results (FIG. 11B). and ACE2-competitive ELISA titers were found to be correlated with pseudovirus neutralization titers across all four strains tested.

The effect of adjuvanted versus non-adjuvanted second doses (boost) was done via factorial analysis based on pseudovirus neutralization titers (FIG. 12A). Animals receiving an adjuvanted boost appeared to induce approximately 2- to 4-fold higher neutralizing antibody titers compared to animals receiving non-adjuvanted boost (antigen-only), demonstrating the positive impact of adjuvants on immune response when utilized for boost.

Immunogenicity of Prototype or B.1.351 S-Trimer™ Booster Doses (Dose 3) in Mice

In Stage 2 of the study (FIG. 10C), animals in Prototype S-Trimer™ prime-boost group were randomized to receive a booster dose (Dose 3) on Day 35 with either Prototype S-Trimer™ or B.1.351 S-Trimer™ (half adjuvanted and half non-adjuvanted). Animals in the heterologous prime-boost group and B.1.351 S-Trimer™ prime-boost group were randomized to receive a booster dose (Dose 3) with either non-adjuvanted Prototype or non-adjuvanted B.1.351 S-Trimer™. Analyses for humoral and cellular immune responses were conducted on Day 49 samples (2 weeks post-dose 3).

Across all vaccine groups after receiving a booster dose, neutralizing antibody titers against the original strain (FIG. 13A) and B.1.1.7 variant (FIG. 13B) pseudoviruses were similar, and fold-increases in titers after the booster (Dose 3) compared to after Dose 2 were also similar across groups. Neutralizing antibody titers increased by about 1.6- to 3.1-fold against the original strain and 1.8- to 2.8-fold against B.1.1.7 variant on average across the booster group.

In the groups receiving three doses of vaccine which included a Prototype S-Trimer™ priming dose (Dose 1), neutralizing antibody titers against the B.1.351 variant pseudovirus (FIG. 13C) increased by 1.7- to 4.6-fold on average after the booster dose, achieving levels comparable to neutralization against the original strain elicited by two doses of Prototype S-Trimer™. We note that variability in B.1.351 neutralization titers in these groups appeared to be higher than neutralization against the other strains tested. In the group receiving three doses of B.1.351 S-Trimer™, neutralizing antibody titers against B.1.351 did not significantly increase after the booster dose, likely because titers were already at high biological levels after the boost (Dose 2).

Interestingly, in the groups perceiving prime-boost with Prototype S-Trimer™ followed by a booster dose (either Prototype S-Trimer™ or B.1.351 S-Trimer™), P.1 neutralization titers (FIG. 13D) did not appear to increase following the booster dose. Similar to B.1.351 neutralization titers, P.1 neutralization titers were numerically highest in the group receiving three doses of B.1.351 S-Trimer™

In the group of animals receiving two doses of Prototype S-Trimer™ vaccine (prime-boost), a subsequent booster dose (Dose 3) with B.1.351 S-Trimer™ did not appear to induce higher neutralizing antibodies against B.1.351 or P.1 compared to animals receiving a booster dose with Prototype S-Trimer™ (FIGS. 13C-13D).

The effect of adjuvanted versus non-adjuvanted booster doses (Dose 3) on humoral immunogenicity in group 1 was conducted using factorial analysis based on pseudovirus neutralization titers (FIG. 12B). Animals receiving an adjuvanted booster dose did not appear to induce significantly higher neutralizing antibody titers compared to animals receiving non-adjuvanted booster doses (antigen-only).

Cell-Mediated Immune Response Induced by 3 Doses of Prototype or B.1.351 S-Trimer™ in Mice

Cell-mediated immune responses were evaluated in animals receiving either three doses of Prototype S-Trimer™ or three doses of B.1.351 S-Trimer™ on Day 49 (2 weeks after dose 3). Cell-mediated immunity (CMI) was assessed by ELISpot detecting Th1 cytokines (IFNγ and IL-2) or Th2 cytokine (IL-5) in harvested mouse splenocytes stimulated with either original (Wuhan-Hu-1) strain S1 peptide pool, SARS-CoV S1 peptide pool, B.1.351 variant RBD peptide pool, or P.1 variant RBD peptide pool.

Strong Th1-biased CMI was observed in both vaccine groups across all stimulants tested (FIGS. 14A-14D). The Th1-biased CMI induced by adjuvanted S-Trimer™ antigen is consistent with results in Liang et al., Nat. Comms., 12:1346, 2021.

Importantly, the magnitude of CMI appeared similar in both vaccine groups across all stimulants, suggesting that broad cross-reactive CMI directed to VOCs (including B.1.1.7, B.1.351 and P.1) can be induced by both the Prototype and B.1.351 S-Trimer™ vaccines. Cross-reactive CMI against SARS-CoV S1 peptide pool (FIG. 14B) did appear to be at levels which were about 40-50% lower than CMI to original strain of SARS-CoV-2 (FIG. 14A), in-line with the 79% sequence homology of the S1 domains for SARS-CoV and SARS-CoV-2.

Discussion Modified B.1.351 S-Trimer™ Vaccine Induces Broad Neutralization Against Original Strain and Variants of Concern

Consistent with results from other studies evaluating prototype COVID-19 vaccines based on the original strain of SARS-CoV-2, in this study Prototype S-Trimer™ prime-boost vaccination induced lower neutralizing antibody titers against B.1.351 and P.1 variants compared to titers against the homologous original SARS-CoV-2 strain (FIGS. 11A-11B). It is believed that the E484K and K417 mutations in the RBD of both B.1.351 and P.1 variants confer immune escape from antibodies induced by prototype vaccines.

Two doses of modified B.1.351 S-Trimer™ antigen induced high levels of neutralizing antibodies against the B.1.351 and P.1 variants. Importantly, two doses of B.1.351 S-Trimer™ was also able to fully back-neutralize against the original SARS-CoV-2 strain, as well as neutralize the B.1.1.7 variant. In contrast, an mRNA COVID-19 vaccine candidate based on the B.1.351 variant spike protein (containing all mutations found in B.1.351) appeared to induce approximately 6-fold lower neutralizing antibody titers against the original SARS-CoV-2 strain compared to the prototype mRNA vaccine in mice (Wu et al., bioRxiv 2021.04.13.439482), and results were consistent in a Phase 1 clinical trial for this B.1.351 mRNA vaccine candidate (Wu et al., N Engl J Med 2021; 384:1468-1470).

The broad neutralization induced by the modified B.1.351 S-Trimer™ vaccine candidate could potentially be explained by the chimeric nature of the antigen sequence, which contains 3 RBD mutations (K417N, E484K, N501Y) and the D614G mutations found in the B.1.351 variant strain, while the NTD and S2 sequences are based on the original SARS-CoV-2 strain (Wuhan-Hu-1) (FIG. 10A). Previous studies have identified neutralizing antibodies that target NTD, and emerging evidence suggests that vaccine-induced anti-NTD neutralizing antibodies are co-dominant with anti-RBD neutralizing antibodies, highlighting the importance of NTD. Thus, the data suggests a potential model for inducing broad neutralization whereby a modified B.1.351 S-Trimer™ antigen could induce (a) anti-RBD antibodies targeting E484K and K417 mutations that can neutralize B.1.351 and P.1 variant strains and (b) anti-NTD antibodies that can neutralize the original strain.

Booster Doses Following Two Doses of Prototype Vaccine could Strengthen Broad Neutralization

Results in this study suggest that a booster dose (with either Prototype S-Trimer™ or B.1.351 S-Trimer™) following two doses of Prototype S-Trimer™ could increase levels of broad neutralizing antibodies against the original strain and VOCs, including B.1.351. There did not appear to be significant differences in neutralizing antibody titers if the booster dose given was Prototype S-Trimer™ or B.1.351 S-Trimer™. Thus, greater flexibility in effective boosting strategies could be employed based on the supply of prototype and variant vaccines available at a given time.

It should also be noted that heterologous prime-boost (Dose 1 Prototype S-Trimer™+Dose 2 B.1.351 S-Trimer™) did not induce higher neutralizing antibody titers against B.1.351 and P.1 compared to animals receiving Prototype S-Trimer™ homologous prime-boost. Furthermore, while a booster dose following Prototype S-Trimer™ prime-boost increased neutralization titers against the B.1.351 variant by about 2.8- to 4.6-fold (compared to post-dose 2 levels), the titers were still numerically lower but also more variable than animals receiving two doses or three doses of B.1.351 S-Trimer™. Additionally, P.1 neutralization titers did not increase in these groups which received Prototype S-Trimer™ prime-boost followed by a booster and remained 2.7- to 4.1-fold lower than the group receiving three doses of B.1.351 S-Trimer™. These results suggest that priming with prototype COVID-19 vaccines may induce some degree of ‘original antigenic sin’, a phenomenon previously-described for other viruses (such as influenza and dengue) whereby the immune system preferentially responds to the epitopes in the priming immunogen and is less able to respond to the new epitopes in the variant (Vatti et al., J. Autoimmun. 83:12-21, 2017). However, cross-reactive neutralizing antibody titers against VOCs in mice induced by Prototype S-Trimer™ prime-boost were still relatively high albeit lower than levels induced by the B.1.351 S-Trimer™ and neutralization titers could be increased with a booster dose.

The results of booster dose in this example support heterologous prime-boost strategies across different platforms, e.g., utilizing protein-based S-Trimer™ as booster doses following primary series of adenovirus-vectored, mRNA, and/or inactivated COVID-19 vaccines. Safety concerns have emerged around the safety of multiple doses of mRNA vaccine related to potential PEG sensitization, and anti-vector immunogenicity for adenovirus-vectored vaccines are known to reduce the effectiveness of subsequent homologous doses. Preliminary human clinical data indicates that heterologous prime-boost with adenovirus-vectored and mRNA COVID-19 vaccines (or vice versa) suggest that they induce higher rates of systemic reactogenicity than heir homologous prime-boost counterparts (Shaw et al., Lancet. (2021) doi:10.1016/50140-6736(21)01115-6).

Broad Cross-Reactive Cell-Mediated Immune Responses Against SARS-CoV-2

While the precise role of cell-mediated immunity (CMI) in the prevention or recovery from COVID-19 remains to be elucidated, there is ample evidence that strong cellular immune responses against the spike (S) protein are induced in COVID-19 patients and that CMI could contribute to the attenuation of symptoms and accelerated clearance of SARS-CoV-2. Furthermore, it has been reported that up to ˜35% of SARS-CoV-2 naïve individuals have some degree of cross-reactive CD4⁺ T-cell responses to SARS-CoV-2 antigens due to prior infection by other common-cold coronaviruses. In this study, while lower levels of neutralizing antibodies against B.1.351 were induced by Prototype S-Trimer™ compared with B.1.351 S-Trimer™, CMI levels appeared to be similar for both vaccine candidates and were cross-reactive for antigens to SARS-CoV-2 (original strain S1, B.1.351 variant RBD, P.1 variant RBD) and SARS-CoV (S1), suggesting that CMI against coronavirus spike proteins could be more broadly cross-reactive than humoral immune responses. The CMI induced by the S-Trimer™ in this study appeared to be Th1-biased in nature, which is consistent with previous studies evaluating adjuvanted Prototype S-Trimer™ (Liang et al., Nat. Comms., 12:1346, 2021; Richmond et al., Lancet, 397: 682-694, 2021).

Use of Adjuvants in Boosting Strategies

Given the high productivity of S-Trimer™ antigens utilizing Trimer-Tag™ technology and the potential to rapidly scale-up production to billions of doses, the potential for “adjuvant sparing,” should the supply of adjuvants be a limiting factor for the availability of COVID-19 vaccines, were evaluated in this study.

Because the use of adjuvants is believed to establish immunological priming, the administration of adjuvanted versus non-adjuvanted second dose (boost) and third dose (booster) doses were evaluated and compared. Animals receiving an adjuvanted boost induced 2-4 fold higher neutralizing antibody titers compared to animals receiving non-adjuvanted boost (antigen-only) (FIG. 12A), suggesting that adjuvants may still be needed for second doses in the primary vaccination series to achieve an optimal immune response. However, animals receiving an adjuvanted booster (third dose) did not appear to induce significantly higher neutralizing antibody titers compared to animals receiving non-adjuvanted booster doses (antigen-only) (FIG. 12B).

Methods Protein Expression and Purification

The Prototype S-Trimer™ and modified B.1.351 S-Trimer™ antigens were produced and purified as previously described (Liang et al., Nat. Comms., 12:1346, 2021) and used for immunogenicity studies. S-Trimer™ antigens based on B.1.1.7 variant and P.1 variant were also produced and used for ACE2-competitive ELISA assays. cDNA encoding the ectodomain of the respective SARS-CoV-2 variant strain Spike (S) proteins were subcloned into the pTRIMER mammalian expression vector to allow in-frame fusion to Trimer-Tag™, which is capable of self-trimerization via disulfide bonds. After transient transfection in 293F cells, the variant S-Trimer™ antigens were expressed and secreted at sufficient levels to enable further characterization and mouse immunogenicity studies. To obtain the variant S-Trimer™ antigens in a highly-purified form for characterization and vaccine studies, an affinity purification scheme as previously described (Liang et al., Nat. Comms., 12:1346, 2021) was utilized to purify the antigens to near homogeneity in a single step.

Receptor Binding Studies of S-Trimer™ to Human ACE2

The binding affinity of S-Trimer™ to ACE2 was assessed by Bio-Layer Interferometry measurements on ForteBio Octet QKe (Pall). ACE2-Fc (10 μg/mL) was immobilized on Protein A (ProA) biosensors (Pall). Real-time receptor-binding curves were obtained by applying the sensor in two-fold serial dilutions of S-Trimer™ (22.5-36 μg/mL in PBS). Kinetic parameters (K_(on) and K_(off)) and affinities (K_(D)) were analyzed using Octet software, version 12.0. Dissociation constants (K_(D)) were determined using steady state analysis, assuming a 1:1 binding model for a S-Trimer™ (Prototype or B.1.351) to ACE2-Fc.

Immunogenicity Analysis of Prototype S-Trimer™ and Modified B.1.351 S-Trimer™ in Mice

BALB/c mice (n=16-32/group) were immunized in Stage 1 of the study with either two doses (Day 0 and Day 21) of Prototype S-Trimer™ (3 μg), heterologous prime-boost (dose 1 Prototype S-Trimer™; dose 2 B.1.351 S-Trimer™; 3 μg of each antigen), two doses B.1.351 S-Trimer™ (3 μg), or two doses of bivalent vaccine (3 μg Prototype S-Trimer™ mixed with 3 μg B.1.351 S-Trimer™). All animals in Stage 1 received an adjuvanted priming dose (Dose 1), whereas half of the animals in each group received an adjuvanted boost (Dose 2), and the other half received non-adjuvanted boost (antigen-only). In Stage 2 of the study, animals in group 1 were randomized to receive a booster (Dose 3 on Day 35) with either 3 μg Prototype or 3 μg B.1.351 S-Trimer™ (half adjuvanted and half non-adjuvanted). Animals in groups 2-3 were randomized to receive a booster (Dose 3) with either 3 μg of non-adjuvanted Prototype or B.1.351 S-Trimer™ In Stage 1, primary analysis for humoral immunogenicity was conducted on day 35 blood samples. In Stage 2, primary analysis for humoral and cellular immune responses was conducted on day 49 blood samples. Animals were bled from tail veins for humoral immune responses analyses. Spleens were removed after sacrifice for ELISpot assays.

ACE2-Competitive ELISA Assays

96-well plates (Corning) were coated with 1 μg/mL ACE2-Fc (100 μL/well) at 4° C. overnight, blocked with 2% non-fat milk 37° C. for 2 h. After washing 3 times with PBST, the plates were incubated with 100 ng/mL S-Trimer™ (Prototype, B.1.351, B.1.1.7 or P.1) mixed with serially diluted antisera for 1 h at 37° C. After washing 3 times with PBST, the plates were incubated with 1:5000 dilution of rabbit anti-Trimer-Tag™ antibody (Clover Biopharmaceuticals) at 37° C. for 1 h, followed by washing 3 times with PBST and then a 1:20000 dilution of goat anti-rabbit IgG-HRP (Southern Biotech). After washing 3 times with PBST, TMB (Thermo Scientific) was added for signal development. The percentage of inhibition was calculated as follows: % inhibition=[(A-Blank)-(P-Blank)]/(A-Blank)×100, where A is the maximum OD signal of S-Trimer™ binding to ACE2-Fc when no serum was present, and P is the OD signal of S-Trimer™ binding to ACE2-Fc in presence of serum at a given dilution. The IC₅₀ of a given serum sample was defined as the reciprocal of the dilution where the sample shows 50% competition.

Pseudovirus Neutralization Assays

SARS-CoV-2 pseudovirus neutralization assay for the original (Wuhan-Hu-1) strain and variant B.1.1.7, B.1.351 and P.1 strains were conducted. To evaluate the SARS-CoV-2 pseudovirus neutralization activity of antisera, samples were first heat-inactivated for 30 min and serially diluted (3-fold), incubated with an equal volume of 650 TCID₅₀ pseudovirus at 37° C. for 1 h, along with virus-alone (positive control) and cell-alone (negative control). Then, freshly-trypsinized ACE2 overexpression-293 cells were added to each well at 20000 cells/well. Following 24 h incubation at 37° C. in a 5% CO₂ incubator, the cells were lysed and luciferase activity was determined by a Luciferase Assay System (Beyotime), according to the manufacturer's protocol. The EC₅₀ neutralizing antibody titer of a given serum sample was defined as the reciprocal of the dilution where the sample showed the relative light units (RLUs) were reduced by 50% compared to virus alone control wells.

Splenocyte Stimulation and ELISpot Assays

To detect antigen-specific T-cell responses, ELISpot kits (Mabtech) measuring Th1 cytokines (IFN-7, IL-2) and Th2 cytokine (IL-5) were used per manufacturer's instructions. Splenocytes from immunized mice or PBMC from immunized mice were harvested 2 weeks after the third immunization. 5×10⁵ splenocytes (96-well plate) were stimulated in vitro with 2 μg/mL of either original SARS-CoV-2 S1 peptide pool, SARS-CoV S1 peptide pool, B.1.351 RBD peptide pool or P.1 RBD peptide pool. Phorbol 12-myristate 13-acetate (PMA) and ionomycin as the non-specific stimulus were added to the positive control wells, whereas the negative control well received no stimuli. After 24-48 h incubation, biotinylated detection antibodies from the ELISpot kits and SA-ALP/SA-HRP were added. Blots were developed by the addition of BCIP/NBT or AEC substrate solution, which produced colored spots after 5-30 min incubation in the dark. The IFN-7, IL-2 and IL-5 spot-forming cells (SFCs) were counted using an automatic ELISpot reader (CTL).

Example 4: Immunogenicity of Adjuvanted SARS-CoV-2 Vaccine

To rapidly express the S-Trimer™ antigen, Trimer-Tag™ technology was employed (Liu et al., Scientific Reports, 7(1): 8953, 2017). cDNA encoding the ectodomain of wild-type SARS-CoV-2 Spike (S) protein was subcloned into the pTRIMER mammalian expression vector to allow in-frame fusion to Trimer-Tag™, which is capable of self-trimerization via disulfide bonds. After stable transfection into CHO cells, subsequent screening for high-titer production clones, and extensive process optimization, a fed-batch serum free cell culture process in bioreactor was developed leading to high-level expression of S-Trimer™ as a secreted protein with a titer around 500 mg/L.

To obtain S-Trimer™ in a highly-purified form for vaccine studies, an affinity purification scheme was developed by taking advantage of the high binding-affinity between Trimer-Tag™ and Endo180, a collagen receptor capable of binding to the C-terminal region of Type 1 procollagen and to mature collagen. Endo180-Fc fusion protein was loaded onto a Protein A column and captured by the resins via high-affinity binding between Protein A and human IgG1 Fc domain of Endo180-Fc. Then, serum-free cell culture medium containing S-Trimer™ secreted by CHO cells was loaded onto the Protein A column with pre-captured Endo180-Fc. After washing off any unbound contaminating host cell proteins (HCP) and other impurities, the bound S-Trimer™ was purified to near homogeneity in a single step using moderate salt elution, conditions that do not dissociate Endo180-Fc from the Protein A column. S-Trimer™ was further purified through low pH for preventative viral inactivation (VI), anion exchange chromatography to remove host cell DNA and any residual endotoxins, nanofiltration as a preventative viral removal (VR) step and finally UF/DF to concentrate S-Trimer™ to the desired concentration in formulation buffer to obtain active drug substance (DS) of S-Trimer™ subunit vaccine candidate was obtained. Stability analysis of purified S-Trimer™ indicates that S-Trimer™ is stable in liquid solution formulations at 2-8° C.

SDS-PAGE analysis under both non-reducing and reducing conditions confirmed that the purified S-Trimer™ was a disulfide bond-linked trimer and partially cleaved at S1/S2 boundary by furin protease, which is produced by CHO cells. Under non-reducing conditions, S-Trimer™ appeared in multiple high molecular weight forms, likely as a result of partial cleavage of the antigen, with non-covalently linked and cleaved S1 released during sample treatment. The reduced form of uncleaved S-Trimer™ has a molecular weight of around 245 kDa. Peptide sequencing via Edman degradation confirmed S1/S2 cleavage between 685R-686S and also revealed that the N-terminal amino acid of S-Trimer™ was blocked after signal peptide cleavage between 13S-14Q, likely via pyroglutamate formation at residual 14Q. This was confirmed by subsequent peptide sequencing after pyroglutamate aminopeptidase removal of 14Q. Protein glycosylation of S-Trimer™ was analyzed by N- and O-linked deglycosylases, which showed extensive N-linked glycosylation at both S1 and S2 regions, accounting for about 32% mass (79 kDa) to be glycans based on molecular weight changes of S2-Trimer™ and S1 before (129 kDa and 116 kDa) and after deglycosylation (93 kDa and 72 kDa). The purity of purified S-Trimer™ was analyzed by size-exclusion SEC-HPLC showing a 96.3% main peak around 700 Kda and a 3.7% minor peak around 180 Kda identified as cleaved S1. The binding affinity (KD) of purified S-Trimer™ to the human ACE2 receptor using ForteBio BioLayer interferometry was shown to be 1.33 nM. Negative-stain EM visualization confirmed that S-Trimer™ particles exist predominantly in a metastable, trimeric pre-fusion form resembling the full-length wild-type spike protein, which was further confirmed by cryo-EM structural studies in the accompanying paper (Ma et al., bioRxiv 2020.09.21.306357. doi:10.1101/2020.09.21.306357).

Detection of SARS-CoV-2 specific binding and neutralizing antibodies in convalescent sera with S-Trimer™. S-Trimer™ was used as an antigen to detect the presence of SARS-CoV-2 Spike protein binding antibodies and ACE2-competitive antibodies in human convalescent sera samples collected from recovered COVID-19 patients. High levels of S-Trimer™ binding antibody and ACE2-competitive titers were detected in the convalescent sera, as well as high neutralizing antibody titers using a pseudovirus neutralization assay. S-Trimer™ binding antibodies were not detected in the sera of naïve human volunteers, whereas antibodies binding to influenza hemagglutinin (HA)-Trimers™ were detected in both COVID-19 convalescent sera and naïve sera, implying prior infection by influenza in all subjects tested but only SARS-CoV-2 infection in the COVID-19 convalescent subjects. These results support the specificity of the assay and demonstrate the ability of S-Trimer™ to detect SARS-CoV-2 Spike protein-specific antibodies in convalescent sera, further confirming the native-like conformation of the Spike antigen in S-Trimer™

Antibody titers were observed to correlate with disease severity, with lower antibody titers observed in patients with mild COVID-19 disease and higher titers in severe cases. Antibody titers also appeared to moderately correlate with patient age, but no differences were observed between genders.

Antibody titers in human convalescent sera were observed to be correlated between the three assays utilized, and these correlations were further confirmed in sera from animals immunized with S-Trimer™. Interestingly, several convalescent sera samples with detectable pseudoviral neutralizing antibody titers did not have any detectable ACE2-competitive titers, suggesting that RBD, which binds to ACE2, is not the only target for neutralizing antibodies, and other domains such as NTD and S2 may also be important antigenic epitopes for viral neutralization.

The immunogenicity of S-Trimer™ was evaluated in BALB/c mice. Mice were vaccinated intramuscularly twice in a two-dose prime-boost regimen (Days 0 and 21) with S-Trimer™ either non-adjuvanted or with various adjuvants. The adjuvant effects on humoral immunogenicity were evident, as S-Trimer™ binding antibody titers, ACE-2 competitive titers and neutralizing antibody titers in the adjuvanted groups were significantly higher than non-adjuvanted vaccine at corresponding antigen dose levels. S-Trimer™ adjuvanted with different adjuvants elicited both ACE2-competitive and pseudovirus neutralizing antibody titers similar to or higher than levels observed in human convalescent sera samples. Similar results were observed in rats immunized with S-Trimer™

S-Trimer™ antigen-specific cell-mediated immunity (CMI) was studied by harvesting splenocytes from immunized mice at sacrifice, followed by stimulation with S-Trimer™ antigen and detection of Th1 (IL-2 and IFNγ) and Th2 (IL-4 and IL-5) cytokines by ELISpot. The adjuvanted groups appeared to induce a stronger overall CMI response than non-adjuvanted S-Trimer™. A Th1-biased cell-mediated immune response was observed across non-adjuvanted and certain adjuvanted S-Trimer™ groups, while a mixed Th1-Th2 profile was observed in other adjuvanted groups. CMI did not appear to be dependent on the dose of antigen.

The immunogenicity of adjuvanted S-Trimer™ was further studied in nonhuman primates (rhesus macaques). Animals were vaccinated intramuscularly twice with adjuvanted S-Trimer™ or a PBS vehicle control. The animals were then challenged on Day 35 with SARS-CoV-2 virus and then evaluated for immune protection by various parameters. High levels of binding and neutralizing antibody titers measured by different methods, including wild-type SARS-CoV-2 virus neutralization assay, were observed in both groups receiving adjuvanted S-Trimer™. The boost-effect of the second dose (on Day 21) was evident, with significant increases in neutralizing antibody levels observed at Day 28 and continuing to rise through Day 35 prior to challenge. At Day 35, neutralizing antibody titers in an adjuvanted S-Trimer™ group were significantly higher than levels in human convalescent sera. Moreover, animals in an adjuvanted S-Trimer™ group appeared to mount a rapid and more durable lymphocyte response that remained high 7 days after viral challenge. Antibody titers post-viral challenge appeared to modestly decrease following challenge at Day 40 (5 dpi), suggesting that challenge with high doses of SARS-CoV-2 may have led to rapid binding of circulating anti-Spike antibodies to the virus and subsequent clearance; a similar trend was reported in convalescent humans that were re-exposed to the virus (Addetia et al., J Clin Microbiol, 21, JCM.021107-20 (2020)).

Following challenge with SARS-CoV-2, animals in the adjuvanted S-Trimer™ groups were protected from body weight loss, whereas animals in the vehicle control group observed rapid body weight loss of approximately 8% through 7 dpi, in line with other reported studies (Munster et al., Nature, 585: 268-272, 2020). Similarly, animals receiving adjuvanted S-Trimer™ appeared to be protected from increases in body temperature following SARS-CoV-2 challenge. Various blood chemistry parameters also suggested that animals in the active vaccine groups may have been protected from organ and tissue damage and other adverse effects of SARS-CoV-2 infection, as animals in the vehicle control group observed increases in blood albumin (ALB), A/G ratio, AST, creatine kinase (CK), glucose (GLU), lactic acid (LAC), and triglycerides (TRIG) through 7 dpi compared to the adjuvanted S-Trimer™ groups.

Lung tissues were harvested at necropsy from 5 to 7 dpi and tested for SARS-CoV-2 viral loads based on genomic RNA (gRNA). Complete reduction of viral loads in lung tissues was observed in adjuvanted S-Trimer™ groups, whereas viral loads were detectable in the vehicle group. Similar trends of reduced viral loads in animals receiving active vaccine were observed from throat swabs, anal swabs and tracheal brushes after challenge through 7 dpi. Viral gRNA detected in nasal swabs were expected given the location of viral challenge and is not necessarily indicative of replicating virus. Histopathological analysis conducted in lung tissues and IHC staining with antibody specific to the Spike protein further confirmed the reduced SARS-CoV-2 infection in animals vaccinated with S-Trimer™

D614G mutation in SARS-CoV-2 Spike protein does not alter receptor binding nor escape from neutralizing antibodies elicited by S-Trimer™. Since SARS-CoV-2 with D614G mutation in the Spike protein has become the predominant circulating strain in many regions of the world, S-Trimer™ with the D614G mutation was also produced. The results showed that, compared to the wild-type S-Trimer™, no significant differences were observed in ACE2 binding affinity, nor ACE2 competitive binding against anti-Spike neutralizing antibodies produced from animals immunized with wild-type S-Trimer™

Immunization of S-Trimer™ with adjuvants induced high-levels of neutralizing antibodies and Th1-biased cellular immune responses in animal models. Moreover, rhesus macaques immunized with adjuvanted S-Trimer™ were protected from SARS-CoV-2 challenge compared to vehicle controls, based on clinical observations and reduction of viral loads in lungs.

Unlike other Spike protein ectodomains used for structural studies and vaccine development, the S-Trimer™ does not include mutations introduced to abolish S1/S2 cleavage by furin protease or to stabilize the protein in a prefusion form. As such, the S-Trimer™ is partially cleaved at the S1/S2 junction, similar to S proteins isolated from live SARS-CoV-2 virus (Gao et al., Science, 369: 77-81, 2020) and recombinant full-length S protein expressed in HEK293 cells (Cai et al., Science, eabd4251, 2020. doi: 10.1126/science.abd425132). As described herein, the S-Trimer™ vaccine candidate, with a fully wild-type S protein ectodomain sequence from SARS-CoV-2, is not only expressed at high levels in CHO cells but also is highly glycosylated and adopts a native-like trimeric pre-fusion conformation. N-terminal protein sequence analysis revealed that upon signal peptide removal during its biosynthesis, S-Trimer™ has N-terminal 14Q modified by pyroglutamate formation to protect itself from exo-protease degradation. Fusion to Trimer-Tag™ allows the soluble wild-type S protein ectodomain to form a disulfide-linked homotrimer with a partially-cleaved S1 that remains noncovalently bound to S-Trimer™. Importantly, the S-Trimer™ maintains high affinity binding to the ACE2 receptor, indicating that crucial antigenic epitopes necessary for viral neutralization are preserved.

The present disclosure is not intended to be limited in scope to the particular disclosed embodiments, which are provided, for example, to illustrate various aspects of the disclosure. Various modifications to the compositions and methods described will become apparent from the description and teachings herein. Such variations may be practiced without departing from the true scope and spirit of the disclosure and are intended to fall within the scope of the present disclosure.

SEQUENCES SEQ ID NO. SEQUENCE DESCRIPTION 1 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 2 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLREFV cleavage site 1 FKNIDGYFKIYSKHTPINLV mutant RDLPQGFSALEPLVDLPIGI (685R→685A) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 3 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, proline PFLMDLEGKQGNFKNLREFV mutant FKNIDGYFKIYSKHTPINLV (986K/987V→ RDLPQGFSALEPLVDLPIGI 4986P/987P) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 4 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLREFV cleavage site 1 FKNIDGYFKIYSKHTPINLV and proline RDLPQGFSALEPLVDLPIGI mutant NITRFQTLLALHRSYLTPGD (685R→685A, SSSGWTAGAAAYYVGYLQPR 986K/987V→986P/ TFLLKYNENGTITDAVDCAL 987p) DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 5 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike NTD/RBD- NGTKRFDNPVLPFNDGVYFA Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 836 aa PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCRSNGLPGPIGPPGPR GRTGDAGPVGPPGPPGPPGP PGPPSAGFDFSFLPQPPQEK AHDGGRYYRANDANVVRDRD LEVDTTLKSLSQQIENIRSP EGSRKNPARTCRDLKMCHSD WKSGEYWIDPNQGCNLDAIK VFCNMETGETCVYPTQPSVA QKNWYISKNPKDKRHVWFGE SMTDGFQFEYGGQGSDPADV AIQLTFLRLMSTEASQNITY HCKNSVAYMDQQTGNLKKAL LLQGSNEIEIRAEGNSRFTY SVTVDGCTSHTGAWGKTVIE YKTTKTSRLPIIDVAPLDVG APDQEFGFDVGPVCFL 6 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S1- NGTKRFDNPVLPFNDGVYFA Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 979 aa PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRSNGLPGPIGPP GPRGRTGDAGPVGPPGPPGP PGPPGPPSAGFDFSFLPQPP QEKAHDGGRYYRANDANVVR DRDLEVDTTLKSLSQQIENI RSPEGSRKNPARTCRDLKMC HSDWKSGEYWIDPNQGCNLD AIKVFCNMETGETCVYPTQP SVAQKNWYISKNPKDKRHVW FGESMTDGFQFEYGGQGSDP ADVAIQLTFLRLMSTEASQN ITYHCKNSVAYMDQQTGNLK KALLLQGSNEIEIRAEGNSR FTYSVTVDGCTSHTGAWGKT VIEYKTTKTSRLPIIDVAPL DVGAPDQEFGFDVGPVCFL 7 SVASQSITAYTMSLGAENSV Prototypic AYSNNSIAIPTNFTISVTTE SARS-CoV-2 ILPVSMTKTSVDCTMYICGD spike S2- STECSNLLLQYGSFCTQLNR Trimer™ ALTGIAVEQDKNTQEVFAQV fusion KQTYKTPPIKDFGGFNFSQI polypeptide, LPDPSKPSKRSFIEDLLFNK 837 aa (cleaved VTLADAGFIKQYGDCLGDIA at S1/S2, site ARDLICAQKFNGLTVLPPLL 1) TDEMIAQYTSALLAGTITSG WTFGAGAALQIPFAMQMAYR FNGIGVTQNVLYENQKLIAN QFNSAIGKIQDSLSSTASAL GKLQDVVNQNAQALNTLVKQ LSSNFGAISSVLNDILSRLD KVEAEVQIDRLITGRLQSLQ TYVTQQLIRAAEIRASANLA ATKMSECVLGQSKRVDFCGK GYHLMSFPQSAPHGVVFLHV TYVPAQEKNFTTAPAICHDG KAHFPREGVFVSNGTHWFVT QRNFYEPQIITTDNTFVSGN CDVVIGIVNNTVYDPLQPEL DSFKEELDKYFKNHTSPDVD LGDISGINASVVNIQKEIDR LNEVAKNLNESLIDLQELGK YEQYIKRSNGLPGPIGPPGP RGRTGDAGPVGPPGPPGPPG PPGPPSAGFDFSFLPQPPQE KAHDGGRYYRANDANVVRDR DLEVDTTLKSLSQQIENIRS PEGSRKNPARTCRDLKMCHS DWKSGEYWIDPNQGCNLDAI KVFCNMETGETCVYPTQPSV AQKNWYISKNPKDKRHVWFG ESMTDGFQFEYGGQGSDPAD VAIQLTFLRLMSTEASQNIT YHCKNSVAYMDQQTGNLKKA LLLQGSNEIEIRAEGNSRFT YSVTVDGCTSHTGAWGKTVI EYKTTKTSRLPIIDVAPLDV GAPDQEFGFDVGPVCFL 8 TMSLGAENSVAYSNNSIAIP Prototypic TNFTISVTTEILPVSMTKTS SARS-CoV-2 VDCTMYICGDSTECSNLLLQ spike S2- YGSFCTQLNRALTGIAVEQD Trimer™ fusion KNTQEVFAQVKQTYKTPPIK polypeptide, DFGGFNFSQILPDPSKPSKR 827 aa (cleaved SFIEDLLFNKVTLADAGFIK at Sl/52, site QYGDCLGDIAARDLICAQKF 2) NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQYIKRSNG LPGPIGPPGPRGRTGDAGPV GPPGPPGPPGPPGPPSAGFD FSFLPQPPQEKAHDGGRYYR ANDANVVRDRDLEVDTTLKS LSQQIENIRSPEGSRKNPAR TCRDLKMCHSDWKSGEYWID PNQGCNLDAIKVFCNMETGE TCVYPTQPSVAQKNWYISKN PKDKRHVWFGESMTDGFQFE YGGQGSDPADVAIQLTFLRL MSTEASQNITYHCKNSVAYM DQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTS HTGAWGKTVIEYKTTKTSRL PIIDVAPLDVGAPDQEFGFD VGPVCFL 9 SFIEDLLFNKVTLADAGFIK Prototypic QYGDCLGDIAARDLICAQKF SARS-CoV-2 NGLTVLPPLLTDEMIAQYTS spike S2- ALLAGTITSGWTFGAGAALQ Trimer™ IPFAMQMAYRFNGIGVTQNV fusion LYENQKLIANQFNSAIGKIQ polypeptide, DSLSSTASALGKLQDVVNQN 707 aa AQALNTLVKQLSSNFGAISS (cleaved VLNDILSRLDKVEAEVQIDR at S2′) LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQYIKRSNG LPGPIGPPGPRGRTGDAGPV GPPGPPGPPGPPGPPSAGFD FSFLPQPPQEKAHDGGRYYR ANDANVVRDRDLEVDTTLKS LSQQIENIRSPEGSRKNPAR TCRDLKMCHSDWKSGEYWID PNQGCNLDAIKVFCNMETGE TCVYPTQPSVAQKNWYISKN PKDKRHVWFGESMTDGFQFE YGGQGSDPADVAIQLTFLRL MSTEASQNITYHCKNSVAYM DQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTS HTGAWGKTVIEYKTTKTSRL PIIDVAPLDVGAPDQEFGFD VGPVCFL 10 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike S-Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 1509 PFLMDLEGKQGNFKNLREFV aa FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 11 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike S-Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 1509 PFLMDLEGKQGNFKNLREFV aa, S1/S2 furin FKNIDGYFKIYSKHTPINLV cleavage site 1 RDLPQGFSALEPLVDLPIGI mutant NITRFQTLLALHRSYLTPGD (685R→685A) SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 12 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike S-Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 1509 PFLMDLEGKQGNFKNLREFV aa, proline FKNIDGYFKIYSKHTPINLV mutant RDLPQGFSALEPLVDLPIGI (986K/ NITRFQTLLALHRSYLTPGD 987V→4986P/ SSSGWTAGAAAYYVGYLQPR 987p) TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 13 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike S-Trimer™ STEKSNIIRGWIFGTTLDSK fusion TQSLLIVNNATNVVIKVCEF polypeptide QFCNDPFLGVYYHKNNKSWM without signal ESEFRVYSSANNCTFEYVSQ peptide, 1509 PFLMDLEGKQGNFKNLREFV aa, S1/S2 furin FKNIDGYFKIYSKHTPINLV cleavage site 1 RDLPQGFSALEPLVDLPIGI and proline NITRFQTLLALHRSYLTPGD mutant SSSGWTAGAAAYYVGYLQPR (685R→685A, TFLLKYNENGTITDAVDCAL 986K/987V→4986P/ DPLSETKCTLKSFTVEKGIY 987N QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 14 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike 5- NGTKRFDNPVLPFNDGVYFA Trimer™ fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa PFLMDLEGKQGNFKNLSEFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 15 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike S- NGTKRFDNPVLPFNDGVYFA Trimer™ fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLSEFV cleavage site 1 FKNIDGYFKIYSKHTPINLV mutant RDLPQGFSALEPLVDLPIGI (685R→685A) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 16 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike S- NGTKRFDNPVLPFNDGVYFA Trimer™ fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, proline PFLMDLEGKQGNFKNLSEFV mutant FKNIDGYFKIYSKHTPINLV (986K/987V→ RDLPQGFSALEPLVDLPIGI 4986P/987P) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 17 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike S- NGTKRFDNPVLPFNDGVYFA Trimer™ fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLSEFV cleavage site 1 FKNIDGYFKIYSKHTPINLV and proline RDLPQGFSALEPLVDLPIGI mutant NITRFQTLLALHRSYLTPGD (685R→685A, SSSGWTAGAAAYYVGYLQPR 986K/987V→4986p/ TFLLKYNENGTITDAVDCAL 987N DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 18 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike S- TKRFDNPVLPFNDGVYFAST Trimer™ fusion EKSNIIRGWIFGTTLDSKTQ polypeptide SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, 1507 EFRVYSSANNCTFEYVSQPF aa LMDLEGKQGNFKNLREFVFK NIDGYFKIYSKHTPINLVRD LPQGFSALEPLVDLPIGINI TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRARSVASQSIIAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQIYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQYIKRSNG LPGPIGPPGPRGRTGDAGPV GPPGPPGPPGPPGPPSAGFD FSFLPQPPQEKAHDGGRYYR ANDANVVRDRDLEVDTTLKS LSQQIENIRSPEGSRKNPAR TCRDLKMCHSDWKSGEYWID PNQGCNLDAIKVFCNMETGE TCVYPTQPSVAQKNWYISKN PKDKRHVWFGESMTDGFQFE YGGQGSDPADVAIQLTFLRL MSTEASQNITYHCKNSVAYM DQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTS HTGAWGKTVIEYKTTKTSRL PIIDVAPLDVGAPDQEFGFD VGPVCFL 19 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike S- TKRFDNPVLPFNDGVYFAST Trimer™ EKSNIIRGWIFGTTLDSKTQ fusion SLLIVNNATNVVIKVCEFQF polypeptide CNDPFLGVYYHKNNKSWMES without signal EFRVYSSANNCTFEYVSQPF peptide, 1507 LMDLEGKQGNFKNLREFVFK aa, S1/S2 furin NIDGYFKIYSKHTPINLVRD cleavage site 1 LPQGFSALEPLVDLPIGINI mutant TRFQTLLALHRSYLTPGDSS (685R→685A) SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRAASVASQSITAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQTYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQYIKRSNG LPGPIGPPGPRGRTGDAGPV GPPGPPGPPGPPGPPSAGFD FSFLPQPPQEKAHDGGRYYR ANDANVVRDRDLEVDTTLKS LSQQIENIRSPEGSRKNPAR TCRDLKMCHSDWKSGEYWID PNQGCNLDAIKVFCNMETGE TCVYPTQPSVAQKNWYISKN PKDKRHVWFGESMTDGFQFE YGGQGSDPADVAIQLTFLRL MSTEASQNITYHCKNSVAYM DQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTS HTGAWGKTVIEYKTTKTSRL PIIDVAPLDVGAPDQEFGFD VGPVCFL 20 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike S- TKRFDNPVLPFNDGVYFAST Trimer™ fusion EKSNIIRGWIFGTTLDSKTQ polypeptide SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, 1507 EFRVYSSANNCTFEYVSQPF aa, proline LMDLEGKQGNFKNLREFVFK mutant (986K/ NIDGYFKIYSKHTPINLVRD 987V→4986P/ LPQGFSALEPLVDLPIGINI 987p) TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRARSVASQSITAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQTYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDPPEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQYIKRSNG LPGPIGPPGPRGRTGDAGPV GPPGPPGPPGPPGPPSAGFD FSFLPQPPQEKAHDGGRYYR ANDANVVRDRDLEVDTTLKS LSQQIENIRSPEGSRKNPAR TCRDLKMCHSDWKSGEYWID PNQGCNLDAIKVFCNMETGE TCVYPTQPSVAQKNWYISKN PKDKRHVWFGESMTDGFQFE YGGQGSDPADVAIQLTFLRL MSTEASQNITYHCKNSVAYM DQQTGNLKKALLLQGSNEIE IRAEGNSRFTYSVTVDGCTS HTGAWGKTVIEYKTTKTSRL PIIDVAPLDVGAPDQEFGFD VGPVCFL 21 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike S- TKRFDNPVLPFNDGVYFAST Trimer™ fusion EKSNIIRGWIFGTTLDSKTQ polypeptide SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, 1507 EFRVYSSANNCTFEYVSQPF aa, S1/S2 furin LMDLEGKQGNFKNLREFVFK cleavage site 1 NIDGYFKIYSKHTPINLVRD and proline LPQGFSALEPLVDLPIGINI mutant TRFQTLLALHRSYLTPGDSS (685R→685A, SGWTAGAAAYYVGYLQPRTF 986K/987V→4986F/ LLKYNENGTITDAVDCALDP 987N LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRAASVASQSIIAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQIYKTP PIKDFGGFNFSQILPDPSKP SKRSFIEDLLFNKVTLADAG FIKQYGDCLGDIAARDLICA QKFNGLTVLPPLLTDEMIAQ YTSALLAGTITSGWTFGAGA ALQIPFAMQMAYRFNGIGVT QNVLYENQKLIANQFNSAIG KIQDSLSSTASALGKLQDVV NQNAQALNTLVKQLSSNFGA ISSVLNDILSRLDPPEAEVQ IDRLITGRLQSLQTYVTQQL IRAAEIRASANLAATKMSEC VLGQSKRVDFCGKGYHLMSF PQSAPHGVVFLHVTYVPAQE KNFTTAPAICHDGKAHFPRE GVFVSNGTHWFVTQRNFYEP QIITTDNTFVSGNCDVVIGI VNNTVYDPLQPELDSFKEEL DKYFKNHTSPDVDLGDISGI NASVVNIQKEIDRLNEVAKN LNESLIDLQELGKYEQYIKR SNGLPGPIGPPGPRGRTGDA GPVGPPGPPGPPGPPGPPSA GFDFSFLPQPPQEKAHDGGR YYRANDANVVRDRDLEVDTT LKSLSQQIENIRSPEGSRKN PARTCRDLKMCHSDWKSGEY WIDPNQGCNLDAIKVFCNME TGETCVYPTQPSVAQKNWYI SKNPKDKRHVWFGESMTDGF QFEYGGQGSDPADVAIQLTF LRLMSTEASQNITYHCKNSV AYMDQQTGNLKKALLLQGSN EIEIRAEGNSRFTYSVTVDG CTSHTGAWGKTVIEYKTTKT SRLPIIDVAPLDVGAPDQEF GFDVGPVCFL 22 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 23 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLREFV cleavage site 1 FKNIDGYFKIYSKHTPINLV mutant RDLPQGFSALEPLVDLPIGI (685R→685A) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 24 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, proline PFLMDLEGKQGNFKNLREFV mutant FKNIDGYFKIYSKHTPINLV (986K/987V→ RDLPQGFSALEPLVDLPIGI 4986P/987p) NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 25 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike S-Trimer™ NGTKRFDNPVLPFNDGVYFA fusion STEKSNIIRGWIFGTTLDSK polypeptide TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, 1509 ESEFRVYSSANNCTFEYVSQ aa, S1/S2 furin PFLMDLEGKQGNFKNLREFV cleavage site 1 FKNIDGYFKIYSKHTPINLV and proline RDLPQGFSALEPLVDLPIGI mutant NITRFQTLLALHRSYLTPGD (685R→685A, SSSGWTAGAAAYYVGYLQPR 986K/987V→4986p/ TFLLKYNENGTITDAVDCAL 987N DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQYIKRS NGLPGPIGPPGPRGRTGDAG PVGPPGPPGPPGPPGPPSAG FDFSFLPQPPQEKAHDGGRY YRANDANVVRDRDLEVDTTL KSLSQQIENIRSPEGSRKNP ARTCRDLKMCHSDWKSGEYW IDPNQGCNLDAIKVFCNMET GETCVYPTQPSVAQKNWYIS KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 26 SDLDRCTTFDDVQAPNYTQH SARS-CoV-1 TSSMRGVYYPDEIFRSDTLY spike S-Trimer™ LTQDLFLPFYSNVTGFHTIN fusion HTFDNPVIPFKDGIYFAATE polypeptide KSNVVRGWVFGSTMNNKSQS without signal VIIINNSTNVVIRACNFELC peptide, 1491 DNPFFAVSKPMGTQTHTMIF aa DNAFNCTFEYISDAFSLDVS EKSGNFKHLREFVFKNKDGF LYVYKGYQPIDVVRDLPSGF NTLKPIFKLPLGINITNFRA ILTAFLPAQDTWGTSAAAYF VGYLKPTTFMLKYDENGTIT DAVDCSQNPLAELKCSVKSF EIDKGIYQTSNFRVVPSRDV VRFPNITNLCPFGEVFNATK FPSVYAWERKRISNCVADYS VLYNSTFFSTFKCYGVSATK LNDLCFSNVYADSFVVKGDD VRQIAPGQTGVIADYNYKLP DDFMGCVLAWNTRNIDATST GNYNYKYRYLRHGKLRPFER DISNVPFSPDGKPCTPPALN CYWPLNDYGFYTTTGIGYQP YRVVVLSFELLNAPATVCGP KLSTDLIKNQCVNFNFNGLT GTGVLTPSSKRFQPFQQFGR DVSDFTDSVRDPKTSEILDI SPCSFGGVSVITPGTNASSE VAVLYQDVNCTDVSTAIHAD QLTPAWRIYSTGNNVFQTQA GCLIGAEHVDTSYECDIPIG AGICASYHTVSLLRSTSQKS IVAYTMSLGADSSIAYSNNT IAIPTNFSISITTEVMPVSM AKTSVDCNMYICGDSTECAN LLLQYGSFCTQLNRALSGIA AEQDRNTREVFAQVKQMYKT PTLKDFGGFNFSQILPDPLK PTKRSFIEDLLFNKVTLADA GFMKQYGECLGDINARDLIC AQKFNGLTVLPPLLTDDMIA AYTAALVSGTATAGWTFGAG AALQIPFAMQMAYRFNGIGV TQNVLYENQKQIANQFNKAI SQIQESLTTTSTALGKLQDV VNQNAQALNTLVKQLSSNFG AISSVLNDILSRLDKVEAEV QIDRLITGRLQSLQTYVTQQ LIRAAEIRASANLAATKMSE CVLGQSKRVDFCGKGYHLMS FPQAAPHGVVFLHVTYVPSQ ERNFTTAPAICHEGKAYFPR EGVFVFNGTSWFITQRNFFS PQIITTDNTFVSGNCDVVIG IINNTVYDPLQPELDSFKEE LDKYFKNHTSPDVDLGDISG INASVVNIQEEIDRLNEVAK NLNESLIDLQELGKYEQYIK RSNGLPGPIGPPGPRGRTGD AGPVGPPGPPGPPGPPGPPS AGFDFSFLPQPPQEKAHDGG RYYRANDANVVRDRDLEVDT TLKSLSQQIENIRSPEGSRK NPARTCRDLKMCHSDWKSGE YWIDPNQGCNLDAIKVFCNM ETGETCVYPTQPSVAQKNWY ISKNPKDKRHVWFGESMTDG FQFEYGGQGSDPADVAIQLT FLRLMSTEASQNITYHCKNS VAYMDQQTGNLKKALLLQGS NEIEIRAEGNSRFTYSVTVD GCTSHTGAWGKTVIEYKTTK TSRLPIIDVAPLDVGAPDQE FGFDVGPVCFL 27 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide QFCNDPFLGVYYHKNNKSWM ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 28 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, S1/S2 QFCNDPFLGVYYHKNNKSWM furin cleavage ESEFRVYSSANNCTFEYVSQ site 1 mutant PFLMDLEGKQGNFKNLREFV (685R→685A) FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 29 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, QFCNDPFLGVYYHKNNKSWM proline mutant ESEFRVYSSANNCTFEYVSQ (986K/987V→ PFLMDLEGKQGNFKNLREFV 4986P/987p) FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 30 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, S1/S2 QFCNDPFLGVYYHKNNKSWM furin cleavage ESEFRVYSSANNCTFEYVSQ site 1 and PFLMDLEGKQGNFKNLREFV proline mutant FKNIDGYFKIYSKHTPINLV (685R→685A, RDLPQGFSALEPLVDLPIGI 986K/987V→ NITRFQTLLALHRSYLTPGD 4986P/ SSSGWTAGAAAYYVGYLQPR 987p) TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 31 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA NTD/RBD STEKSNIIRGWIFGTTLDSK fragment TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKC 32 QCVNLTTRTQLPPAYTNSFT Prototypic RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA S1 fragment STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide QFCNDPFLGVYYHKNNKSWM ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ DVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSP 33 SVASQSITAYTMSLGAENSV Prototypic AYSNNSIAIPTNFTISVTTE SARS-CoV-2 ILPVSMTKTSVDCTMYICGD spike protein STECSNLLLQYGSFCTQLNR S2 fragment ALTGIAVEQDKNTQEVFAQV (cleaved at KQTYKTPPIKDFGGFNFSQI S1/S2, site 1) LPDPSKPSKRSFIEDLLFNK VTLADAGFIKQYGDCLGDIA ARDLICAQKFNGLTVLPPLL TDEMIAQYTSALLAGTITSG WTFGAGAALQIPFAMQMAYR FNGIGVTQNVLYENQKLIAN QFNSAIGKIQDSLSSTASAL GKLQDVVNQNAQALNTLVKQ LSSNFGAISSVLNDILSRLD KVEAEVQIDRLITGRLQSLQ TYVTQQLIRAAEIRASANLA ATKMSECVLGQSKRVDFCGK GYHLMSFPQSAPHGVVFLHV TYVPAQEKNFTTAPAICHDG KAHFPREGVFVSNGTHWFVT QRNFYEPQIITTDNTFVSGN CDVVIGIVNNTVYDPLQPEL DSFKEELDKYFKNHTSPDVD LGDISGINASVVNIQKEIDR LNEVAKNLNESLIDLQELGK YEQ 34 TMSLGAENSVAYSNNSIAIP Prototypic TNFTISVTTEILPVSMTKTS SARS-CoV-2 VDCTMYICGDSTECSNLLLQ spike protein YGSFCTQLNRALTGIAVEQD S2 fragment KNTQEVFAQVKQTYKTPPIK (cleaved at DFGGFNFSQILPDPSKPSKR S1/S2, site 2) SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 35 SFIEDLLFNKVTLADAGFIK Prototypic QYGDCLGDIAARDLICAQKF SARS-CoV-2 NGLTVLPPLLTDEMIAQYTS spike protein ALLAGTITSGWTFGAGAALQ S2 fragment IPFAMQMAYRFNGIGVTQNV (cleaved at LYENQKLIANQFNSAIGKIQ S2′) DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 36 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 37 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, S1/S2 ESEFRVYSSANNCTFEYVSQ furin cleavage PFLMDLEGKQGNFKNLREFV site 1 mutant FKNIDGYFKIYSKHTPINLV (685R→685A) RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 38 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, ESEFRVYSSANNCTFEYVSQ proline mutant PFLMDLEGKQGNFKNLREFV (986K/987V→ FKNIDGYFKIYSKHTPINLV 4986P/887P) RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 39 QCVNLTTRTQLPPAYTNSFT B.1.351 South RGVYYPDKVFRSSVLHSTQD African variant LFLPFFSNVTWFHAIHVSGT SARS-CoV-2 NGTKRFDNPVLPFNDGVYFA spike protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNDPFLGVYYHKNNKSWM peptide, S1/S2 ESEFRVYSSANNCTFEYVSQ furin cleavage PFLMDLEGKQGNFKNLREFV site 1 and FKNIDGYFKIYSKHTPINLV proline mutant RDLPQGFSALEPLVDLPIGI (685R→685A, NITRFQTLLALHRSYLTPGD 986K/987V→4986P/ SSSGWTAGAAAYYVGYLQPR 987N TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGNIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 40 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike NGTKRFDNPVLPFNDGVYFA protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLSEFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 41 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike NGTKRFDNPVLPFNDGVYFA protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, S1/S2 ESEFRVYSSANNCTFEYVSQ furin cleavage PFLMDLEGKQGNFKNLSEFV site 1 mutant FKNIDGYFKIYSKHTPINLV (685R→685A) RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 42 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike NGTKRFDNPVLPFNDGVYFA protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, ESEFRVYSSANNCTFEYVSQ proline mutant PFLMDLEGKQGNFKNLSEFV (986K/987V→ FKNIDGYFKIYSKHTPINLV 4986P/987p) RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 43 QCVNFTNRTQLPSAYTNSFT P.1 Brazilian RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAIHVSGT CoV-2 spike NGTKRFDNPVLPFNDGVYFA protein STEKSNIIRGWIFGTTLDSK ectodomain TQSLLIVNNATNVVIKVCEF without signal QFCNYPFLGVYYHKNNKSWM peptide, S1/S2 ESEFRVYSSANNCTFEYVSQ furin cleavage PFLMDLEGKQGNFKNLSEFV site 1 and FKNIDGYFKIYSKHTPINLV proline mutant RDLPQGFSALEPLVDLPIGI (685R→685A, NITRFQTLLALHRSYLTPGD 986K/987V→4986P/ SSSGWTAGAAAYYVGYLQPR 987N TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGTIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVKGFNCYFPLQ SYGFQPTYGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EYVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAAIKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 44 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike TKRFDNPVLPFNDGVYFAST protein EKSNIIRGWIFGTTLDSKTQ ectodomain SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide EFRVYSSANNCTFEYVSQPF LMDLEGKQGNFKNLREFVFK NIDGYFKIYSKHTPINLVRD LPQGFSALEPLVDLPIGINI TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRARSVASQSIIAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQIYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 45 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike TKRFDNPVLPFNDGVYFAST protein EKSNIIRGWIFGTTLDSKTQ ectodomain SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, S1/S2 EFRVYSSANNCTFEYVSQPF furin cleavage LMDLEGKQGNFKNLREFVFK site 1 mutant NIDGYFKIYSKHTPINLVRD (685R→685A) LPQGFSALEPLVDLPIGINI TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRAASVASQSIIAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQIYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDKVEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 46 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike TKRFDNPVLPFNDGVYFAST protein EKSNIIRGWIFGTTLDSKTQ ectodomain SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, EFRVYSSANNCTFEYVSQPF proline mutant LMDLEGKQGNFKNLREFVFK (986K/987V→ NIDGYFKIYSKHTPINLVRD 4986P/987P) LPQGFSALEPLVDLPIGINI TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRARSVASQSIIAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQIYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDPPEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 47 QCVNLTTRTQLPPAYTNSFT B.1.1.7 UK RGVYYPDKVFRSSVLHSTQD variant SARS- LFLPFFSNVTWFHAISGTNG CoV-2 spike TKRFDNPVLPFNDGVYFAST protein EKSNIIRGWIFGTTLDSKTQ ectodomain SLLIVNNATNVVIKVCEFQF without signal CNDPFLGVYYHKNNKSWMES peptide, S1/S2 EFRVYSSANNCTFEYVSQPF furin cleavage LMDLEGKQGNFKNLREFVFK site 1 and NIDGYFKIYSKHTPINLVRD proline mutant LPQGFSALEPLVDLPIGINI (685R→685A, TRFQTLLALHRSYLTPGDSS 986K/987V→ SGWTAGAAAYYVGYLQPRTF 4986P/987N LLKYNENGTITDAVDCALDP LSETKCTLKSFTVEKGIYQT SNFRVQPTESIVRFPNITNL CPFGEVFNATRFASVYAWNR KRISNCVADYSVLYNSASFS TFKCYGVSPTKLNDLCFTNV YADSFVIRGDEVRQIAPGQT GKIADYNYKLPDDFTGCVIA WNSNNLDSKVGGNYNYLYRL FRKSNLKPFERDISTEIYQA GSTPCNGVEGFNCYFPLQSY GFQPTYGVGYQPYRVVVLSF ELLHAPATVCGPKKSTNLVK NKCVNFNFNGLTGTGVLTES NKKFLPFQQFGRDIADTTDA VRDPQTLEILDITPCSFGGV SVITPGTNTSNQVAVLYQGV NCTEVPVAIHADQLTPTWRV YSTGSNVFQTRAGCLIGAEH VNNSYECDIPIGAGICASYQ TQTNSHRRAASVASQSITAY TMSLGAENSVAYSNNSIAIP TNFTISVTTEILPVSMTKTS VDCTMYICGDSTECSNLLLQ YGSFCTQLNRALTGIAVEQD KNTQEVFAQVKQTYKTPPIK DFGGFNFSQILPDPSKPSKR SFIEDLLFNKVTLADAGFIK QYGDCLGDIAARDLICAQKF NGLTVLPPLLTDEMIAQYTS ALLAGTITSGWTFGAGAALQ IPFAMQMAYRFNGIGVTQNV LYENQKLIANQFNSAIGKIQ DSLSSTASALGKLQDVVNQN AQALNTLVKQLSSNFGAISS VLNDILSRLDPPEAEVQIDR LITGRLQSLQTYVTQQLIRA AEIRASANLAATKMSECVLG QSKRVDFCGKGYHLMSFPQS APHGVVFLHVTYVPAQEKNF TTAPAICHDGKAHFPREGVF VSNGTHWFVTQRNFYEPQII TTDNTFVSGNCDVVIGIVNN TVYDPLQPELDSFKEELDKY FKNHTSPDVDLGDISGINAS VVNIQKEIDRLNEVAKNLNE SLIDLQELGKYEQ 48 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide QFCNDPFLGVYYHKNNKSWM ESEFRVYSSANNCTFEYVSQ PFLMDLEGKQGNFKNLREFV FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 49 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, S1/S2 QFCNDPFLGVYYHKNNKSWM furin cleavage ESEFRVYSSANNCTFEYVSQ site 1 mutant PFLMDLEGKQGNFKNLREFV (685R→685A) FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSIT AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQTYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDKVEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 50 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, QFCNDPFLGVYYHKNNKSWM proline mutant ESEFRVYSSANNCTFEYVSQ (986K/987V→ PFLMDLEGKQGNFKNLREFV 4986P/987P) FKNIDGYFKIYSKHTPINLV RDLPQGFSALEPLVDLPIGI NITRFQTLLALHRSYLTPGD SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRARSVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 51 QCVNLTTRTQLPPAYTNSFT D614G variant RGVYYPDKVFRSSVLHSTQD SARS-CoV-2 LFLPFFSNVTWFHAIHVSGT spike protein NGTKRFDNPVLPFNDGVYFA ectodomain STEKSNIIRGWIFGTTLDSK without signal TQSLLIVNNATNVVIKVCEF peptide, S1/S2 QFCNDPFLGVYYHKNNKSWM furin cleavage ESEFRVYSSANNCTFEYVSQ site 1 and PFLMDLEGKQGNFKNLREFV proline mutant FKNIDGYFKIYSKHTPINLV (685R→685A, RDLPQGFSALEPLVDLPIGI 986K/987V→ NITRFQTLLALHRSYLTPGD 4986P/987p) SSSGWTAGAAAYYVGYLQPR TFLLKYNENGTITDAVDCAL DPLSETKCTLKSFTVEKGIY QTSNFRVQPTESIVRFPNIT NLCPFGEVFNATRFASVYAW NRKRISNCVADYSVLYNSAS FSTFKCYGVSPTKLNDLCFT NVYADSFVIRGDEVRQIAPG QTGKIADYNYKLPDDFTGCV IAWNSNNLDSKVGGNYNYLY RLFRKSNLKPFERDISTEIY QAGSTPCNGVEGFNCYFPLQ SYGFQPTNGVGYQPYRVVVL SFELLHAPATVCGPKKSTNL VKNKCVNFNFNGLTGTGVLT ESNKKFLPFQQFGRDIADTT DAVRDPQTLEILDITPCSFG GVSVITPGTNTSNQVAVLYQ GVNCTEVPVAIHADQLTPTW RVYSTGSNVFQTRAGCLIGA EHVNNSYECDIPIGAGICAS YQTQTNSPRRAASVASQSII AYTMSLGAENSVAYSNNSIA IPTNFTISVTTEILPVSMTK TSVDCTMYICGDSTECSNLL LQYGSFCTQLNRALTGIAVE QDKNTQEVFAQVKQIYKTPP IKDFGGFNFSQILPDPSKPS KRSFIEDLLFNKVTLADAGF IKQYGDCLGDIAARDLICAQ KFNGLTVLPPLLTDEMIAQY TSALLAGTITSGWTFGAGAA LQIPFAMQMAYRFNGIGVTQ NVLYENQKLIANQFNSAIGK IQDSLSSTASALGKLQDVVN QNAQALNTLVKQLSSNFGAI SSVLNDILSRLDPPEAEVQI DRLITGRLQSLQTYVTQQLI RAAEIRASANLAATKMSECV LGQSKRVDFCGKGYHLMSFP QSAPHGVVFLHVTYVPAQEK NFTTAPAICHDGKAHFPREG VFVSNGTHWFVTQRNFYEPQ IITTDNTFVSGNCDVVIGIV NNTVYDPLQPELDSFKEELD KYFKNHTSPDVDLGDISGIN ASVVNIQKEIDRLNEVAKNL NESLIDLQELGKYEQ 52 SDLDRCTTFDDVQAPNYTQH SARS-CoV-1 TSSMRGVYYPDEIFRSDTLY spike protein LTQDLFLPFYSNVTGFHTIN ectodomain HTFDNPVIPFKDGIYFAATE without signal KSNVVRGWVFGSTMNNKSQS peptide VIIINNSTNVVIRACNFELC DNPFFAVSKPMGTQTHTMIF DNAFNCTFEYISDAFSLDVS EKSGNFKHLREFVFKNKDGF LYVYKGYQPIDVVRDLPSGF NTLKPIFKLPLGINITNFRA ILTAFLPAQDTWGTSAAAYF VGYLKPTTFMLKYDENGTIT DAVDCSQNPLAELKCSVKSF EIDKGIYQTSNFRVVPSRDV VRFPNITNLCPFGEVFNATK FPSVYAWERKRISNCVADYS VLYNSTFFSTFKCYGVSATK LNDLCFSNVYADSFVVKGDD VRQIAPGQTGVIADYNYKLP DDFMGCVLAWNTRNIDATST GNYNYKYRYLRHGKLRPFER DISNVPFSPDGKPCTPPALN CYWPLNDYGFYTTTGIGYQP YRVVVLSFELLNAPATVCGP KLSTDLIKNQCVNFNFNGLT GTGVLTPSSKRFQPFQQFGR DVSDFTDSVRDPKTSEILDI SPCSFGGVSVITPGTNASSE VAVLYQDVNCTDVSTAIHAD QLTPAWRIYSTGNNVFQTQA GCLIGAEHVDTSYECDIPIG AGICASYHTVSLLRSTSQKS IVAYTMSLGADSSIAYSNNT IAIPTNFSISITTEVMPVSM AKTSVDCNMYICGDSTECAN LLLQYGSFCTQLNRALSGIA AEQDRNTREVFAQVKQMYKT PTLKDFGGFNFSQILPDPLK PTKRSFIEDLLFNKVTLADA GFMKQYGECLGDINARDLIC AQKFNGLTVLPPLLTDDMIA AYTAALVSGTATAGWTFGAG AALQIPFAMQMAYRFNGIGV TQNVLYENQKQIANQFNKAI SQIQESLTTTSTALGKLQDV VNQNAQALNTLVKQLSSNFG AISSVLNDILSRLDKVEAEV QIDRLITGRLQSLQTYVTQQ LIRAAEIRASANLAATKMSE CVLGQSKRVDFCGKGYHLMS FPQAAPHGVVFLHVTYVPSQ ERNFTTAPAICHEGKAYFPR EGVFVFNGTSWFITQRNFFS PQIITTDNTFVSGNCDVVIG IINNTVYDPLQPELDSFKEE LDKYFKNHTSPDVDLGDISG INASVVNIQEEIDRLNEVAK NLNESLIDLQELGKYEQ 53 MFIFLLFLTLTSG SARS-CoV-1 spike protein signal peptide 54 MFVFLVLLPLVSS Prototypic SARS-CoV-2 spike protein signal peptide 55 MFVFLVLLPLVSSQCVNLTT Prototypic RTQLPPAYTNSFTRGVYYPD SARS-CoV-2 KVFRSSVLHSTQDLFLPFFS full-length NVTWFHAIHVSGTNGTKRFD spike protein, NPVLPFNDGVYFASTEKSNI 1273 aa IRGWIFGTTLDSKTQSLLIV NNATNVVIKVCEFQFCNDPF LGVYYHKNNKSWMESEFRVY SSANNCTFEYVSQPFLMDLE GKQGNFKNLREFVFKNIDGY FKIYSKHTPINLVRDLPQGF SALEPLVDLPIGINITRFQT LLALHRSYLTPGDSSSGWTA GAAAYYVGYLQPRTFLLKYN ENGTITDAVDCALDPLSETK CTLKSFTVEKGIYQTSNFRV QPTESIVRFPNITNLCPFGE VFNATRFASVYAWNRKRISN CVADYSVLYNSASFSTFKCY GVSPTKLNDLCFTNVYADSF VIRGDEVRQIAPGQTGKIAD YNYKLPDDFTGCVIAWNSNN LDSKVGGNYNYLYRLFRKSN LKPFERDISTEIYQAGSTPC NGVEGFNCYFPLQSYGFQPT NGVGYQPYRVVVLSFELLHA PATVCGPKKSTNLVKNKCVN FNFNGLTGTGVLTESNKKFL PFQQFGRDIADTTDAVRDPQ TLEILDITPCSFGGVSVITP GTNTSNQ VAVLYQDVNCTEVPVAIHAD QLTPTWRVYSTGSNVFQTRA GCLIGAEHVNNSYECDIPIG AGICASYQTQTNSPRRARSV ASQSITAYTMSLGAENSVAY SNNSIAIPTNFTISVTTEIL PVSMTKTSVDCTMYICGDST ECSNLLLQYGSFCTQLNRAL TGIAVEQDKNTQEVFAQVKQ TYKTPPIKDFGGFNFSQILP DPSKPSKRSFIEDLLFNKVT LADAGFIKQYGDCLGDIAAR DLICAQKFNGLTVLPPLLTD EMIAQYTSALLAGTITSGWT FGAGAALQIPFAMQM AYRFNGIGVTQNVLYENQKL IANQFNSAIGKIQDSLSSTA SALGKLQDVVNQNAQALNTL VKQLSSNFGAISSVLNDILS RLDKVEAEVQIDRLITGRLQ SLQTYVTQQLIRAAEIRASA NLAATKMSECVLGQSKRVDF CGKGYHLMSFPQSAPHGVVF LHVTYVPAQEKNFTTAPAIC HDGKAHFPREGVFVSNGTHW FVTQRNFYEPQIITTDNTFV SGNCDVVIGIVNNTVYDPLQ PELDSFKEELDKYFKNHTSP DVDLGDISGINASVVNIQKE IDRLNEVAKNLNESLIDLQE LGKYEQYIKWPWYIWLGFIA GLIAIVMVTIMLCCMTSCCS CLKGCCSCGSCCKFDEDDSE PVLKGVKLHYT 56 MFVFLVLLPLVSSQCVNLTT Prototypic RTQLPPAYTNSFTRGVYYPD SARS-CoV-2 KVFRSSVLHSTQDLFLPFFS spike protein NVTWFHAIHVSGTNGTKRFD ectodomain with NPVLPFNDGVYFASTEKSNI signal peptide IRGWIFGTTLDSKTQSLLIV NNATNVVIKVCEFQFCNDPF LGVYYHKNNKSWMESEFRVY SSANNCTFEYVSQPFLMDLE GKQGNFKNLREFVFKNIDGY FKIYSKHTPINLVRDLPQGF SALEPLVDLPIGINITRFQT LLALHRSYLTPGDSSSGWTA GAAAYYVGYLQPRTFLLKYN ENGTITDAVDCALDPLSETK CTLKSFTVEKGIYQTSNFRV QPTESIVRFPNITNLCPFGE VFNATRFASVYAWNRKRISN CVADYSVLYNSASFSTFKCY GVSPTKLNDLCFTNVYADSF VIRGDEVRQIAPGQTGKIAD YNYKLPDDFTGCVIAWNSNN LDSKVGGNYNYLYRLFRKSN LKPFERDISTEIYQAGSTPC NGVEGFNCYFPLQSYGFQPT NGVGYQPYRVVVLSFELLHA PATVCGPKKSTNLVKNKCVN FNFNGLTGTGVLTESNKKFL PFQQFGRDIADTTDAVRDPQ TLEILDITPCSFGGVSVITP GTNTSNQVAVLYQDVNCTEV PVAIHADQLTPTWRVYSTGS NVFQTRAGCLIGAEHVNNSY ECDIPIGAGICASYQTQTNS PRRARSVASQSITAYTMSLG AENSVAYSNNSIAIPTNFTI SVTTEILPVSMTKTSVDCTM YICGDSTECSNLLLQYGSFC TQLNRALTGIAVEQDKNTQE VFAQVKQTYKTPPIKDFGGF NFSQILPDPSKPSKRSFIED LLFNKVTLADAGFIKQYGDC LGDIAARDLICAQKFNGLTV LPPLLTDEMIAQYTSALLAG TITSGWTFGAGAALQIPFAM QMAYRFNGIGVTQNVLYENQ KLIANQFNSAIGKIQDSLSS TASALGKLQDVVNQNAQALN TLVKQLSSNFGAISSVLNDI LSRLDKVEAEVQIDRLITGR LQSLQTYVTQQLIRAAEIRA SANLAATKMSECVLGQSKRV DFCGKGYHLMSFPQSAPHGV VFLHVTYVPAQEKNFTTAPA ICHDGKAHFPREGVFVSNGT HWFVTQRNFYEPQIITTDNT FVSGNCDVVIGIVNNTVYDP LQPELDSFKEELDKYFKNHT SPDVDLGDISGINASVVNIQ KEIDRLNEVAKNLNESLIDL QELGKYEQ 57 VNLTTRTQLPPAYTNSFTRG Prototypic VYYPDKVFRSSVLHSTQDLF SARS-CoV-2 LPFFSNVTWFHAIHVSGTNG spike protein TKRFDNPVLPFNDGVYFAST NTD without EKSNIIRGWIFGTTLDSKTQ signal peptide, SLLIVNNATNVVIKVCEFQF 290 aa CNDPFLGVYYHKNNKSWMES EFRVYSSANNCTFEYVSQPF LMDLEGKQGNFKNLREFVFK NIDGYFKIYSKHTPINLVRD LPQGFSALEPLVDLPIGINI TRFQTLLALHRSYLTPGDSS SGWTAGAAAYYVGYLQPRTF LLKYNENGTITDAVDCALDP LSETKCTLKS 58 PNITNLCPFGEVFNATRFAS Prototypic VYAWNRKRISNCVADYSVLY SARS-CoV-2 NSASFSTFKCYGVSPTKLND spike protein LCFTNVYADSFVIRGDEVRQ RBD, 192 aa IAPGQTGKIADYNYKLPDDF TGCVIAWNSNNLDSKVGGNY NYLYRLFRKSNLKPFERDIS TEIYQAGSTPCNGVEGFNCY FPLQSYGFQPTNGVGYQPYR VVVLSFELLHAP 59 RRAR Prototypic SARS-CoV-2 spike protein S1/S2 60 GSAG Prototypic SARS-CoV-2 spike protein S1/S2 mutant 61 SFIEDLLFNKVTLADAGF Prototypic SARS-CoV-2 spike protein fusion peptide (FP) sequence 62 GIGVTQNVLYENQKLIANQF Prototypic NSAIGKIQDSLSSTASALGK SARS-CoV-2 LQDVVNQNAQALNTLVKQLS spike protein SNFGAISSVLNDILSRLD heptad repeat 1 (HR1) 63 KVEAEVQIDRLITGRLQSLQ Prototypic TYVTQQLIRAAEIRASANLA SARS-CoV-2 ATKMSECVLG spike protein central helix (CH) 64 TTAPAICHDGKAHFPREGVF Prototypic VSNGTHWFVTQRNFYEPQII SARS-CoV-2 TTDNTFVSGNCDVVIGIVNN spike protein TVYDPL connector domain (CD) 65 EELDKYFKNHTSPDVDLGDI Prototypic SGINASVVNIQKEIDRLNEV SARS-CoV-2 AKNLNESLIDLQELGKYEQ spike protein heptad repeat 2 (HR2) 66 WPWYIWLGFIAGLIAIVMVT Prototypic IML SARS-CoV-2 spike protein transmembrane (TM) domain 67 ANVVRDRDLEVDTTLKSLSQ Trimerization QIENIRSPEGSRKNPARTCR peptide (Type DLKMCHSDWKSGEYWIDPNQ I), QT version GCNLDAIKVFCNMETGETCV YPTQPSVAQKNWYISKNPKD KRHVWFGESMTDGFQFEYGG QGSDPADVAIQLTFLRLMST EASQNITYHCKNSVAYMDQQ TGNLKKALLLQGSNEIEIRA EGNSRFTYSVTVDGCTSHTG AWGKTVIEYKTTKTSRLPII DVAPLDVGAPDQEFGFDVGP VCFL 68 NGLPGPIGPPGPRGRTGDAG Trimerization PVGPPGPPGPPGPPGPPSAG peptide (Type FDFSFLPQPPQEKAHDGGRY I), with YRANDANVVRDRDLEVDTTL glycine-X-Y KSLSQQIENIRSPEGSRKNP repeats and D→N ARTCRDLKMCHSDWKSGEYW mutation at IDPNQGCNLDAIKVFCNMET BMP-1 site, QT GETCVYPTQPSVAQKNWYIS version KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 69 NGLPGPIGPPGPRGRTGDAG Trimerization PVGPPGPPGPPGPPGPPSAG peptide (Type FDFSFLPQPPQEKAHDGGRY I), with YRNDDANVVRDRDLEVDTTL glycine-X-Y KSLSQQIENIRSPEGSRKNP repeats and A→N ARTCRDLKMCHSDWKSGEYW mutation at IDPNQGCNLDAIKVFCNMET BMP-1 site, QT GETCVYPTQPSVAQKNWYIS version KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLQGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKTS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 70 RSNGLPGPIGPPGPRGRTGD Trimerization AGPVGPPGPPGPPGPPGPPS peptide (Type AGFDFSFLPQPPQEKAHDGG I), with RYYRANDANVVRDRDLEVDT glycine-X-Y TLKSLSQQIENIRSPEGSRK repeats and D→N NPARTCRDLKMCHSDWKSGE mutation at YWIDPNQGCNLDAIKVFCNM BMP-1 site, QT ETGETCVYPTQPSVAQKNWY version ISKNPKDKRHVWFGESMTDG FQFEYGGQGSDPADVAIQLT FLRLMSTEASQNITYHCKNS VAYMDQQTGNLKKALLLQGS NEIEIRAEGNSRFTYSVTVD GCTSHTGAWGKTVIEYKTTK TSRLPIIDVAPLDVGAPDQE FGFDVGPVCFL 71 GSNGLPGPIGPPGPRGRTGD Trimerization AGPVGPPGPPGPPGPPGPPS peptide (Type AGFDFSFLPQPPQEKAHDGG I), with RYYRANDANVVRDRDLEVDT glycine-X-Y TLKSLSQQIENIRSPEGSRK repeats and D→N NPARTCRDLKMCHSDWKSGE mutation at YWIDPNQGCNLDAIKVFCNM BMP-1 site, QT ETGETCVYPTQPSVAQKNWY version ISKNPKDKRHVWFGESMTDG FQFEYGGQGSDPADVAIQLT FLRLMSTEASQNITYHCKNS VAYMDQQTGNLKKALLLQGS NEIEIRAEGNSRFTYSVTVD GCTSHTGAWGKTVIEYKTTK TSRLPIIDVAPLDVGAPDQE FGFDVGPVCFL 72 ANVVRDRDLEVDTTLKSLSQ Trimerization QIENIRSPEGSRKNPARTCR peptide (Type DLKMCHSDWKSGEYWIDPNQ I), KS version GCNLDAIKVFCNMETGETCV YPTQPSVAQKNWYISKNPKD KRHVWFGESMTDGFQFEYGG QGSDPADVAIQLTFLRLMST EASQNITYHCKNSVAYMDQQ TGNLKKALLLKGSNEIEIRA EGNSRFTYSVTVDGCTSHTG AWGKTVIEYKTTKSSRLPII DVAPLDVGAPDQEFGFDVGP VCFL 73 NGLPGPIGPPGPRGRTGDAG Trimerization PVGPPGPPGPPGPPGPPSAG peptide (Type FDFSFLPQPPQEKAHDGGRY I) with YRANDANVVRDRDLEVDTTL glycine-X-Y KSLSQQIENIRSPEGSRKNP repeats and D→N ARTCRDLKMCHSDWKSGEYW mutation at IDPNQGCNLDAIKVFCNMET BMP-1 site, KS GETCVYPTQPSVAQKNWYIS version KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLKGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKSS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 74 NGLPGPIGPPGPRGRTGDAG Trimerization PVGPPGPPGPPGPPGPPSAG peptide (Type FDFSFLPQPPQEKAHDGGRY I) with YRNDDANVVRDRDLEVDTTL glycine-X-Y KSLSQQIENIRSPEGSRKNP repeats and A→N ARTCRDLKMCHSDWKSGEYW at IDPNQGCNLDAIKVFCNMET BMP-1 site, KS GETCVYPTQPSVAQKNWYIS version KNPKDKRHVWFGESMTDGFQ FEYGGQGSDPADVAIQLTFL RLMSTEASQNITYHCKNSVA YMDQQTGNLKKALLLKGSNE IEIRAEGNSRFTYSVTVDGC TSHTGAWGKTVIEYKTTKSS RLPIIDVAPLDVGAPDQEFG FDVGPVCFL 75 RSNGLPGPIGPPGPRGRTGD Trimerization AGPVGPPGPPGPPGPPGPPS peptide (Type AGFDFSFLPQPPQEKAHDGG I) with RYYRANDANVVRDRDLEVDT glycine-X-Y TLKSLSQQIENIRSPEGSRK repeats and D→N NPARTCRDLKMCHSDWKSGE mutation at YWIDPNQGCNLDAIKVFCNM BMP-1 site, KS ETGETCVYPTQPSVAQKNWY version ISKNPKDKRHVWFGESMTDG FQFEYGGQGSDPADVAIQLT FLRLMSTEASQNITYHCKNS VAYMDQQTGNLKKALLLKGS NEIEIRAEGNSRFTYSVTVD GCTSHTGAWGKTVIEYKTTK SSRLPIIDVAPLDVGAPDQE FGFDVGPVCFL 76 GSNGLPGPIGPPGPRGRTGD Trimerization AGPVGPPGPPGPPGPPGPPS peptide (Type AGFDFSFLPQPPQEKAHDGG I) with RYYRANDANVVRDRDLEVDT glycine-X-Y TLKSLSQQIENIRSPEGSRK repeats and D→N NPARTCRDLKMCHSDWKSGE mutation at YWIDPNQGCNLDAIKVFCNM BMP-1 site, KS ETGETCVYPTQPSVAQKNWY version ISKNPKDKRHVWFGESMTDG FQFEYGGQGSDPADVAIQLT FLRLMSTEASQNITYHCKNS VAYMDQQTGNLKKALLLKGS NEIEIRAEGNSRFTYSVTVD GCTSHTGAWGKTVIEYKTTK SSRLPIIDVAPLDVGAPDQE FGFDVGPVCFL 77 DEIMTSLKSVNGQIESLISP Trimerization DGSRKNPARNCRDLKFCHPE peptide (Type LKSGEYWVDPNQGCKLDAIK III) VFCNMETGETCISANPLNVP RKHWWTDSSAEKKHVWFGES MDGGFQFSYGNPELPEDVLD VQLAFLRLLSSRASQNITYH CKNSIAYMDQASGNVKKALK LMGSNEGEFKAEGNSKFTYT VLEDGCTKHTGEWSKTVFEY RTRKAVRLPIVDIAPYDIGG PDQEFGVDVGPVCF 78 EPMDFKINTDEIMTSLKSVN Trimerization GQIESLISPDGSRKNPARNC peptide (Type RDLKFCHPELKSGEYWVDPN III) QGCKLDAIKVFCNMETGETC ISANPLNVPRKHWWTDSSAE KKHVWFGESMDGGFQFSYGN PELPEDVLDVQLAFLRLLSS RASQNITYHCKNSIAYMDQA SGNVKKALKLMGSNEGEFKA EGNSKFTYTVLEDGCTKHTG EWSKTVFEYRTRKAVRLPIV DIAPYDIGGPDQEFGVDVGP VCFL 79 SEPMDFKINTDEIMTSLKSV Trimerization NGQIESLISPDGSRKNPARN peptide (Type CRDLKFCHPELKSGEYWVDP III) NQGCKLDAIKVFCNMETGET CISANPLNVPRKHWWTDSSA EKKHVWFGESMDGGFQFSYG NPELPEDVLDVQLAFLRLLS SRASQNITYHCKNSIAYMDQ ASGNVKKALKLMGSNEGEFK AEGNSKFTYTVLEDGCTKHT GEWSKTVFEYRTRKAVRLPI VDIAPYDIGGPDQEFGVDVG PVCFL 80 RSEPMDFKINTDEIMTSLKS Trimerization VNGQIESLISPDGSRKNPAR peptide (Type NCRDLKFCHPELKSGEYWVD III) PNQGCKLDAIKVFCNMETGE TCISANPLNVPRKHWWTDSS AEKKHVWFGESMDGGFQFSY GNPELPEDVLDVQLAFLRLL SSRASQNITYHCKNSIAYMD QASGNVKKALKLMGSNEGEF KAEGNSKFTYTVLEDGCTKH TGEWSKTVFEYRTRKAVRLP IVDIAPYDIGGPDQEFGVDV GPVCFL 

1-62. (canceled)
 63. A fusion polypeptide comprising a SARS-CoV-2 spike (S) ectodomain polypeptide and a C-propeptide of a human pro-collagen, wherein the C-propeptide is configured to form a disulfide bond-linked homotrimer.
 64. The fusion polypeptide of claim 63, wherein the human pro-collagen is selected from the group consisting of proα1(I), proα1(II), proα1(III), proα1(V), proα1(XI), proα2(I), proα2(V), proα2(XI), and proα3(XI).
 65. The fusion polypeptide of claim 63, wherein the fusion polypeptide further comprises a glycine-repeat triple helical region of collagen linked to the C-propeptide.
 66. The fusion polypeptide of claim 63, wherein the fusion polypeptide does not comprise a BMP-1 protease recognition sequence or comprises a mutated BMP-1 protease recognition sequence.
 67. The fusion polypeptide of claim 63, wherein the SARS-CoV-2 S ectodomain polypeptide comprises an S1 sequence and/or an S2 sequence.
 68. The fusion polypeptide of claim 63, wherein the SARS-CoV-2 S ectodomain polypeptide comprises a furin cleavage site mutation and/or one or more proline substitutions between an HR1 domain and a central helix domain.
 69. The fusion polypeptide of claim 63, wherein the SARS-CoV-2 S ectodomain polypeptide comprises a receptor binding domain (RBD) sequence and/or an N-terminal domain (NTD) sequence.
 70. The fusion polypeptide of claim 69, wherein the NTD sequence and the RBD sequence are independently selected from the group consisting of the NTD and RBD sequences of the B.1.526, B.1.1.143, P.2, B.1.351, P.1, B.1.1.7, B.1.617, and A.23.1 lineages of SARS-CoV-2.
 71. The fusion polypeptide of claim 70, wherein the NTD sequence is from a SARS-CoV-2 of the B.1.526 lineage, and the RBD sequence is from a SARS-CoV-2 of the B.1.351 lineage.
 72. A trimeric fusion protein comprising the fusion polypeptide of claim 63, wherein the trimeric fusion protein comprises interchain disulfide bonds.
 73. The trimeric fusion protein of claim 72, wherein the fusion polypeptide comprises a sequence set forth in any one of SEQ ID NOs: 27-51, 54, and 56-65.
 74. The trimeric fusion protein of claim 72, wherein the fusion polypeptide comprises a sequence set forth in any of SEQ ID NOs: 67-80.
 75. The trimeric fusion protein of claim 72, which is a homotrimer of a sequence selected from the group consisting of SEQ ID NOs: 1-25 and comprises interchain disulfide bonds among the C-propeptide sequences.
 76. The trimeric fusion protein of claim 72, which is a recombinant subunit vaccine optionally comprising one or more adjuvants.
 77. A method of generating an immune response in a subject, comprising administering to the subject an effective amount of a homotrimer of a fusion polypeptide comprising a SARS-CoV-2 spike (S) ectodomain polypeptide and a C-propeptide of a human pro-collagen, wherein the homotrimer comprises interchain disulfide bonds among the C-propeptide sequences, and wherein the immune response is to the SARS-CoV-2 S ectodomain polypeptide or a fragment or epitope thereof.
 78. The method of claim 77, wherein the immune response comprise generation of a neutralizing antibody to a SARS-CoV-2.
 79. The method of claim 78, wherein the neutralizing antibody is a monoclonal antibody.
 80. The method of claim 78, wherein the neutralizing antibody comprises polyclonal antibodies.
 81. The method of claim 77, wherein the homotrimer is administered via intramuscular injection.
 82. The method of claim 77, wherein the homotrimer is administered via intra-nasal spray.
 83. The method of claim 77, wherein the homotrimer is administered in a single dose or a series of doses separated by intervals of weeks or months.
 84. The method of claim 77, wherein the homotrimer is administered without an adjuvant.
 85. The method of claim 77, wherein the homotrimer is administered with one or more adjuvants.
 86. The method of claim 77, which prevents infection of the subject by one, two, three or more SARS-CoV-2 viruses.
 87. The method of claim 86, wherein the one, two, three or more SARS-CoV-2 viruses are of the B.1.526, B.1.1.143, P.2, B.1.351, P.1, B.1.1.7, B.1.617, or A.23.1 lineage.
 88. The method of claim 77, wherein the fusion polypeptide comprises a sequence selected from the group consisting of SEQ ID NOs: 1-25.
 89. The method of claim 88, which prevents infection of the subject by a SARS-CoV-2 comprising a sequence set forth in any one of SEQ ID NOs: 27-51 and 54-65.
 90. The method of claim 77, wherein the homotrimer is administered as a booster dose following one or more doses of a vaccine for SARS-CoV-2.
 91. The method of claim 77, wherein the homotrimer is administered at a unit dose between 3 μg and 30 μg of the homotrimer.
 92. The method of claim 77, further comprising detecting a neutralizing antibody to a SARS-CoV-2 in the subject following the administration. 